Web bug

A Web bug is an object that is embedded in a web page or e-mail and is usually invisible to the user but allows checking that a user has viewed the page or e-mail. One common use is in e-mail tracking. Alternative names are Web beacon, tracking bug, tracking pixel, pixel tag, 1×1 gif, and clear gif.

A Web bug is any one of a number of techniques used to track who is reading a Web page or e-mail, when, and from what computer. They can also be used to see if an e-mail was read or forwarded to someone else, or if a Web page was copied to another Website. The first Web bugs were small images.

Some e-mails and Web pages are not wholly self-contained. They may refer to content on another server, rather than including the content directly. When an e-mail client or web browser prepares such an e-mail or Web page for display, it ordinarily sends a request to the server to send the additional content.

These requests typically include the IP address of the requesting computer, the time the content was requested, the type of Web browser that made the request, and the existence of cookies previously set by that server. The server can store all of this information, and associate it with a unique tracking token attached to the content request.

E-mail Web bugs

Web bugs embedded in e-mails have greater privacy implications than bugs embedded in Web pages. Typically, the URL of Web bugs contained in e-mail messages carry a unique identifier. This identifier is chosen when the e-mail is sent, and is recorded together with the recipient e-mail address. The later download of the URL signals that the e-mail has been read. The sender of the e-mail is therefore also able to record the exact time that a message was read, as well as the IP address of the computer used to read the mail or the proxy server that the user went through. In this way, the sender can gather detailed information about when, and from where, each particular recipient reads e-mail. Additionally, every time the e-mail message is displayed, another request may go to the sender's Web site.

Web bugs are used by e-mail marketers, spammers, and phishers to verify that e-mail addresses are valid, that the content of e-mails has made it past the spam filters, and that the e-mail is actually viewed by users. When the user reads the e-mail, the e-mail client requests the image, letting the sender know that the e-mail address is valid and that e-mail was viewed. The e-mail need not contain an advertisement or anything else related to the commercial activity of the sender. This makes detection of such e-mails harder for mail filters and users.

Tracking via Web bugs can be prevented by using e-mail clients that do not download images whose URLs are embedded in HTML e-mails. Many graphical e-mail clients can be configured to avoid accessing remote images. Examples include the Gmail, Yahoo!, and SpamCop/Horde webmail clients; Mozilla Thunderbird, Opera, Pegasus Mail, IncrediMail, later versions of Microsoft Outlook, and KMail mail readers. Other HTML techniques (such as IFrames) can still be used to track e-mail viewing.

Wide Area Information Servers

Wide Area Information Servers or WAIS is a client-server text searching system that uses the ANSI Standard Z39.50 Information Retrieval Service Definition and Protocol Specifications for Library Application (Z39.50:1988) to search index databases on remote computers. It was developed in the late 1980s as a project of Thinking Machines, Apple Computer, Dow Jones, and KPMG Peat Marwick.

WAIS did not adhere to either the standard or its OSI framework (adopting instead TCP/IP) but created a unique protocol inspired by Z39.50:1988.

The WAIS protocol and servers were primarily promoted by Thinking Machines Corporation of Cambridge, Massachusetts. Thinking Machines produced WAIS servers which ran on their massively parallel CM-2 (connection machine) and SPARC-based CM-5 MP supercomputers. WAIS clients were developed for various operating systems including Windows, Macintosh, NeXT and UNIX. TMC, however, released a free open source version of WAIS to run on Unix in 1991.

Inspired by the WAIS project on full text databases and emerging SGML projects Z39.50 version 2 or Z39.50:1992 was released. Unlike its 1988 predecessor it was a compatible superset of the ISO 10162/10163 work that had been done internationally.

With the advent of Z39.50:1992, the termination of support for the free WAIS from Thinking Machines and the establishment of WAIS Inc as a commercial venture (their WAIS was written to use the Fulcrum fulltext engine), the U.S. National Science Foundation funded CNIDR to create a clearinghouse of information related to Internet search and discovery systems and to promote open source and standards. CNIDR created a new freely available open-source WAIS. This created first the freeWAIS package based on the wais-8-b5 codebase implemented by Thinking Machines Corp and then a wholly new software suite Isite based upon Z39.50:1992 with Isearch as its full text search engine.

Ulrich Pfeifer and Norbert Gövert of the computer science department of the University of Dortmund took the CNIDR freeWAIS code and extended it to become freeWAIS-sf: sf means structured fields and indicated its main improvement. Ulrich Pfeifer rewrote freeWAIS-sf in Perl where it became WAIT.

Server Message Block

In computer networking, Server Message Block (SMB) operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an authenticated Inter-process communication mechanism. Most usage of SMB involves computers running Microsoft Windows, where it is often known as "Microsoft Windows Network".

When discussing SMB, one should distinguish:

* the SMB protocol
* the SMB services that run on the protocol
* NetBIOS
* the DCE/RPC services that use SMB as an authenticated Inter-process communication channel (over named pipes)
* the "Network Neighborhood" protocols which primarily (but not exclusively) run as datagram services directly on the NetBIOS transport

Smokeless Tobacco

Many people who chew tobacco or dip snuff think it's safer than smoking. But you don't have to smoke tobacco for it to be dangerous. Chewing or dipping carries risks like

* Cancer of the mouth
* Decay of exposed tooth roots
* Pulling away of the gums from the teeth
* White patches or red sores in the mouth that can turn to cancer

Recent research shows the dangers of smokeless tobacco may go beyond the mouth. It might also play a role in other cancers, heart disease and stroke.

Smokeless tobacco contains more nicotine than cigarettes. Nicotine is a highly additive drug that makes it hard to stop using tobacco once you start. Having a quit date and a quitting plan can help you stop successfully.

Contact Lens-improve defective vision

Contact Lenses are simple to wear and care for, and are almost undetectable. They are thin discs of plastic, curved on the inside to fit properly onto the surface of the eye, and shaped on the outside to correct and improve defective vision, for bandaging the eye after surgery, and cosmetic benefits e.g. to cover white scarring of the eye or to change the colour of the eye for fashion. With advancing technology Contact Lenses can correct all forms of visual defects including Astigmatism safely and comfortably. There are basically two types of contact lenses : Rigid and Soft. Both types come in varying materials with different levels of oxygen permeabilities. The higher the oxygen permeability the better it is for the eye.

Rubella-lu-like symptoms

Rubella is an illness with flu-like symptoms followed by a rash. Common symptoms include

* Low-grade fever
* Headache
* Runny nose
* Red eyes
* Muscle or joint pain

Rubella is usually mild. You may get it and not even know it. However, adults who get rubella often feel sicker than children do. The biggest danger of rubella is if a woman gets it during the first 20 weeks of pregnancy. She may lose the baby, or the virus could cause problems to her unborn baby. Those problems could include cataracts, deafness or damage to the heart or brain.

A virus causes rubella. It can spread from one person to another through the air or through close contact with someone who has it. There is no treatment for rubella, but the measles-mumps-rubella (MMR) vaccine can prevent it.

Campus area network (CAN)

A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.

In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN).

The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base.

Computer network nodes

In data communication, a node may either be a data circuit-terminating equipment (DCE) such as a modem, hub, bridge or switch; or a data terminal equipment (DTE) such as a digital telephone handset, a printer or a host computer, for example a router, a workstation or a server.

If the network in question is the Internet, many network nodes are host computers, identified by an IP address, and all hosts are nodes. However, datalink layer devices such as switches, bridges and WLAN access points do not have an IP host address (except sometimes for administrative purposes), and are not considered as Internet nodes, but as network nodes.

If the network in question is a peer-to-peer or overlay network, nodes that actively route data for the other networked devices as well as themselves are called supernodes. Nodes that route between supernodes are commonly referred to as "super-duper" nodes.

Buses in system

Buses can be parallel buses, which carry data words in parallel on multiple wires, or serial buses, which carry data in bit-serial form. The addition of extra power and control connections, differential drivers, and data connections in each direction usually means that most serial buses have more conductors than the minimum of one used in the 1-Wire serial bus. As data rates increase, the problems of timing skew, power consumption, electromagnetic interference and crosstalk across parallel buses become more and more difficult to circumvent.

One partial solution to this problem has been to double pump the bus. Often, a serial bus can actually be operated at higher overall data rates than a parallel bus, despite having fewer electrical connections, because a serial bus inherently has no timing skew or crosstalk. USB, FireWire, and Serial ATA are examples of this. Multidrop connections do not work well for fast serial buses, so most modern serial buses use daisy-chain or hub designs.

Most computers have both internal and external buses. An internal bus connects all the internal components of a computer to the motherboard. These types of buses are also referred to as a local bus, because they are intended to connect to local devices, not to those in other machines or external to the computer. An external bus connects external peripherals to the motherboard.

Universal Serial Bus

Universal Serial Bus (USB) is a serial bus standard to connect devices to a host computer. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve plug and play capabilities by allowing hot swapping; that is, by allowing devices to be connected and disconnected without rebooting the computer or turning off the device. Other convenient features include providing power to low-consumption devices, eliminating the need for an external power supply; and allowing many devices to be used without requiring manufacturer-specific device drivers to be installed.

USB is intended to replace many varieties of serial and parallel ports. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, flash drives, and external hard drives. For many of those devices, USB has become the standard connection method. USB was designed for personal computers, but it has become commonplace on other devices such as PDAs and video game consoles, and as a power cord between a device and an AC adapter plugged into a wall plug for charging. As of 2008[update], there are about 2 billion USB devices sold per year, and about 6 billion total sold to date.

World Wide Web Consortium

The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web (abbreviated WWW or W3). It is arranged as a consortium where member organizations maintain full-time staff for the purpose of working together in the development of standards for the World Wide Web. As of February 2008, the W3C had 434 members.

W3C also engages in education and outreach, develops software and serves as an open forum for discussion about the Web. It was founded and is headed by Sir Tim Berners-Lee.

The World Wide Web Consortium (W3C) was founded by Tim Berners-Lee after he left the European Organization for Nuclear Research (CERN) in October, 1994. It was founded at the Massachusetts Institute of Technology Laboratory for Computer Science (MIT/LCS) with support from the Defense Advanced Research Projects Agency (DARPA) -- which had pioneered the Internet -- and the European Commission.

Opera (Web browser)

Opera is a web browser and Internet suite developed by the Opera Software company. Opera handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, IRC online chatting, downloading files via BitTorrent, and reading web feeds. Opera is offered free of charge for personal computers and mobile phones, but for other devices it must be paid for.

Features of Opera include tabbed browsing, page zooming, mouse gestures, and an integrated download manager. Its security features include built-in phishing and malware protection, strong encryption when browsing secure web sites, and the ability to easily delete private data such as cookies and browsing history by simply clicking a button.

Opera runs on a variety of personal computer operating systems, including Microsoft Windows, Mac OS X, Linux, FreeBSD, and Solaris. Though evaluations of Opera have been largely positive, Opera has captured only a fraction of the worldwide personal computer browser market.

Opera has a stronger market share, however, on mobile devices such as mobile phones, smartphones, and personal digital assistants. Editions of Opera are available for devices using the Symbian and Windows Mobile operating systems, as well as Java ME-enabled devices. In fact, approximately 40 million mobile phones have shipped with Opera pre-installed. Furthermore, Opera is the only commercial web browser available for the Nintendo DS and Wii gaming systems. Some television set-top boxes use Opera as well, and Adobe licensed Opera technology for use in the Adobe Creative Suite.

URI scheme-Uniform Resource Identifier

In the field of computer networking, a URI scheme is the top level of the Uniform Resource Identifier (URI) naming structure. All URIs and absolute URI references are formed with a scheme name, followed by a colon character (":"), and the remainder of the URI called (in the outdated RFCs 1738 and 2396, but not the current STD 66/RFC 3986) the scheme-specific part. The syntax and semantics of the scheme-specific part are left largely to the specifications governing individual schemes, subject to certain constraints such as reserved characters and how to "escape" them.

URI schemes are sometimes erroneously referred to as "protocols", or specifically as URI protocols or URL protocols, since most were originally designed to be used with a particular protocol, and often have the same name. The http scheme, for instance, is generally used for interacting with Web resources using HyperText Transfer Protocol. Today, URIs with that scheme are also used for other purposes, such as RDF resource identifiers and XML namespaces, that are not related to the protocol. Furthermore, some URI schemes are not associated with any specific protocol (e.g. "file") and many others do not use the name of a protocol as their prefix (e.g. "news").

URI schemes should be registered with IANA, although non-registered schemes are used in practice. RFC 4395 describes the procedures for registering new URI schemes.

The World Wide Web Consortium

The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web (abbreviated WWW or W3). It is arranged as a consortium where member organizations maintain full-time staff for the purpose of working together in the development of standards for the World Wide Web. As of February 2008, the W3C had 434 members.W3C also engages in education and outreach, develops software and serves as an open forum for discussion about the Web. It was founded and is headed by Sir Tim Berners-Lee.

Spreadsheet

A table of values arranged in rows and columns. Each value can have a predefined relationship to the other values. If you change one value, therefore, you may need to change other values as well.

Spreadsheet applications are computer programs that let you create and manipulate spreadsheets electronically. In a spreadsheet application, each value sits in a cell. You can define what type of data is in each cell and how different cells depend on one another. The relationships between cells are called formulas, and the names of the cells are called labels.

Once you have defined the cells and the formulas for linking them together, you can enter your data. You can then modify selected values to see how all the other values change accordingly. This enables you to study various what-if scenarios.

Mosaic (web browser)

Mosaic is the web browser credited with popularizing the World Wide Web. It was also a client for earlier protocols such as FTP, Usenet, and Gopher. Its clean, easily understood user interface, reliability, Windows port and simple installation all contributed to making it the application that opened up the Web to the general public. Mosaic was also the first browser to display images inline with text instead of displaying images in a separate window.

Mosaic was developed at the National Center for Supercomputing Applications (NCSA) beginning in late 1992. NCSA released the browser in 1993, and officially discontinued development and support on January 7, 1997. However, it can still be downloaded from NCSA.

Mosaic was the final link in the chain of technologies (TCP, IP, ftp | nntp | gopher | http, URL, HTML, etc.) which Tim Berners-Lee had earlier brought together to invent the World Wide Web. After the appearance of Mosaic the concept of the World Wide Web took off globally at an explosive rate.

ViolaWWW

Viola WWW, first developed in the early 1990s, was the first popular WWW web browser (though to a limited audience) which, until Mosaic, was the most frequently used web browser for access to the World Wide Web.Gillies and Cailliau in How the Web was Born offer an extensive history of the development of Viola. Viola was the invention of Pei-Yuan Wei, who at the time was a student at the University of California, Berkeley.

Created in 1992, it was the first browser to use authoring technology such as embedded script able objects, style sheets, and tables. According to Gilles and Cailliau "Viola was to become the first X-browser to make any impact, but even his early versions went down well at CERN...As this Viola WWW developed, it was to set the standard for everything to follow it." Ed Kroll also highlighted it in his popular 1992 text, Whole Internet User's Guide and Catalog.

Cascading Style Sheets

Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including SVG and XUL.

CSS can be used locally by the readers of web pages to define colors, fonts, layout, and other aspects of document presentation. It is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation (written in CSS). This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, and reduce complexity and repetition in the structural content (such as by allowing for table less web design).

Link rot

Link rot (or linkrot) is the process by which links on a website gradually become irrelevant or broken as time goes on, because websites that they link to disappear, change their content or redirect to new locations.

The phrase also describes the effects of failing to update web pages so that they become out-of-date, containing information that is old and useless, and that clutters up search engine results.

Detecting link rot for a given URL is difficult using automated methods. If a URL is accessed and returns back an HTTP 200 (OK) response, it may be considered accessible, but the contents of the page may have changed and may no longer be relevant. Some web servers also return a soft 404, a page returned with a 200 (OK) response (instead of a 404) that indicates the URL is no longer accessible. Bar-Yossef et al. (2004) developed a heuristic for automatically discovering soft 404s.

C (programming language)

In computing, C is a general-purpose computer programming language originally developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories to implement the Unix operating system.Although C was designed for writing architecturally independent system software,it is also widely used for developing application software.

Worldwide, C is the first or second most popular language in terms of number of developer positions or publicly available code. It is widely used on many different software platforms, and there are few computer architectures for which a C compiler does not exist. C has greatly influenced many other popular programming languages, most notably C++, which originally began as an extension to C, and Java and C# which borrow C lexical conventions and ope.

NeXTdimension

NeXTdimension (ND) was an accelerated 32 bit color board manufactured and sold by NeXT from 1990 that gave the NeXTcube color capabilities with PostScript. The NuBus card was a full size card for the NeXTcube, filling one of four slots, another one being filled with the main board itself. The NeXTdimension featured S-Video input and output, RGB output, an Intel i860 64 bit RISC processor at 33MHz for Postscript acceleration, 8-32MB RAM main memory and 4MB VRAM for a resolution of 1120*832 at 24 bit color plus 8 bit alpha channel. An onboard C-Cube CL550 chip for MJPEG video compression was announced, but never shipped. A handful of engineering prototypes for the MJPEG daughterboard exist, but none actually function.

A stripped down Mach kernel was used as the operating system for the card. Due to the supporting processor 32 bit color Display PostScript on the NeXTdimension was faster than 2 bit grayscale Display PostScript on the NeXTcube. Since the main board always included the grayscale video logic, adding a NeXTdimension allowed the simultaneous use of two monitors. List price for a NeXTdimension sold as an add-on to the NeXTcube was $US 3,995.

Netscape Navigator

Netscape Navigator and Netscape are the names for the proprietary web browser popular in the 1990s, and the flagship product of the Netscape Communications Corporation, and the dominant web browser in terms of usage share. Yet by 2002 its users had almost disappeared, partly because of Microsoft's bundling (inclusion) of its Internet Explorer web browser software with the Windows operating system software (both Microsoft products), and partly because Netscape corporation did not sustain Netscape Navigator's technical innovation after the late 1990s.

The business demise of Netscape was a central premise of Microsoft's antitrust trial, wherein, the Court ruled that Microsoft corporation's bundling of Internet Explorer with the Windows operating system was monopolistic, an illegal business practice.