This Glossary is a companion to the Emerging Web series. It covers terms that are of importance in todays and tomorrows World Wide Web, and to a lesser extent terms that were of importance in the past, or about the Internet in general.
Words that are described elsewhere in the glossary are marked with emphasis.
A
- ARPANET
- Conceived in 1969, this was the first network of what later would become the network of networks : the Internet. It was initiated by the US military organisation ARPA, later known as DARPA
- AJAX
- Stands for Asynchronous Javascript and XML. It is a method of combining a number of technologies that allows a website to communicate with the server and update itself without needing to reload the whole page. This communication with the server happens asynchronous, which means the user can be performing different tasks on the page while the new content is loading in the background. The communication back and forth is through the XML data format standard. This method became possible once most common browsers had a usable implementation of the XmlHttpRequest javascript object. There is some critique, since it has become extremely hyped while there’s really no new technology in it. This also breaks the browsers back button which can be confusing for the user.
B
- Breadcrumb
- Named after the trail of breadcrumbs Hans and Gretel left to find their way back, a breadcrumb or breadcrumb trail is a part of a user interface that shows the path to the current document. Many websites with hierarchical content use this, for instance “Home >> Category >> Article”.
C
- CERN
- Centre Europeen de Recherche Nucleair / European Center for Nuclear Research. A Geneva based research center where the World Wide Web was invented.
D
- DARPA
- Originally known as ARPA, the Defense Advanced Research Project Agency is a US governmental organisation that does scientific research for the US military. They are responsible for creating the first computer network, ARPANET, and the first hypertext system named NLS, the great grandfather of the current World Wide Web
F
- Folksonomy
- A combination of the words folk and taxonomy. It refers to the way tagging (see Tag) allows users to categorize information, be it websites, photographs or something else. This way collaboratively structure can be given to big collections of (user provided) data, that is both human and machine readable. Good examples are the sites Flickr and del.icio.us.
H
- HTML
- Hypertext Markup Language. A text-based standard to structure documents on the Web. HTML uses HTML-tags to declare parts of the document as being lists, tables, links, images, etc. A webbrowser will use this information, together with specific style information, to render and display the page. By using the approach where simple text is augmented with markup and style, it is possible for non-graphical browsers, such as text-based browsers, screen readers (for blind people), or braille readers (for blind people) to still ‘display’ the page. This however asks considerable discipline from the website designer. See also Accesibility.
- HTTP
- Hypertext Transfer Protocol. Protocol originally developed by Tim Berners-Lee and Robert Cailiau to request and retrieve documents from a webserver. It is the core application protocol of the World Wide Web
- Hyperlink
- A link in a hypertext document, for example a link in a webpage, which can be followed to another document.
- Hypertext
- Is a user interface paradigm, where documents are given an interactive character. Most notable are hyperlinks, which allow one document to point to another document. The user can ‘follow the link’, and will end up viewing the referred document. In 1945 a very influential essay was published titled ‘As We May Think’ by Vannevar Bush. The author predicted many types of new technology, and the essay can be seen as laying the philosophical foundation for hypertext systems including the World Wide Web. He argued that ‘as humans turned from war, scientific efforts should shift from increasing physical abilities to making all previous collected human knowledge more accessible.’ (source : Wikipedia). See also HTML, URL, Hyperlink
I
- Internet
- Global network of networks. The first network of what later would become the Internet was ARPANET. Some of the applications that make use of the infrastructure the Internet delivers are e-mail, World Wide Web, Instant Messaging, Newsgroups and Peer-to-Peer file sharing, amongst others. All devices connected to the Internet communicate through the Internet Protocol (IP) and can be identified by a unique IP address.
- IP
- IP stands for Internet Protocol. It is the unifying protocol of the Internet. IP is a bit like a postal service. Every computer on the Internet has a unique ‘IP address’. To send some information from one computer to another, the information is put into a virtual envelope called an IP ‘packet’. The computer then puts its own (IP) address on the envelope, as well as the destination address. The envelope is delivered to your Internet Service Provider (a bit like the Postal Service), which will take care of getting it to the addressee. The packet will be passed on by many computers (known as routers) each one a bit closer to the destination, until it finally can be delivered. IP only delivers a bare-bone communication service. When sending a packet, there is no way to be certain it has actually reached its destination. When sending multiple messages, they might even arrive in a completely different order. IP is a network protocol, it takes care of locating the designated host on the huge network that is todays Internet. For more advanced control over the communication IP is augmented with ‘transport protocols‘, most importantly TCP.
M
- Mashup
- An application (possibly web-based) that combines several webservices from different sources to create new possibilitys. Often uses AJAX as glue.
N
- Newsgroup
- see Usenet
P
- Protocol
- A protocol in computer networking is a set of conventions that declare how communicating entities will communicate. It defines the type of messages that can be transmitted, who can transmit or receive at a given moment and the structure and meaning of the messages. Protocols can be stacked, this means a message of one protocol is placed inside the message of a different protocol. To give a highly simplified example : when you are visiting a webpage, your webbrowser is communicating with the webserver through the HTTP protocol. A typical HTTP message is ’send me page XYZ’. When the browser (program) sends this message to the server (program), your computer will place this message inside one or more IP ‘packets’. Through the Internet these packets will be delivered to the server computer. It will unpack these IP packets, reconstruct the original message (’send me page XYZ’), and deliver it to the server program. In a similar way the server sends the result to your webbrowser. Common protocols on the Internet include amongst others : IP, TCP and UDP for low level communications, POP, IMAP and SMTP for sending and retrieving emails, HTTP and FTP for file transfer, Jabber for instant messaging, IRC for chatting
R
- Rich Internet Application
- Can be abbreviated to RIA. A rich internet application is an application that works inside a browser, yet provides more advanced functionality than the classic webpage paradigm allows. Possible ways to achieve this is by using Flash, AJAX, Microsofts ActiveX or Java Applets. The first two are the most popular, since general browser support is lacking for the latter two.
- Robert Cailiau
- Invented the World Wide Web together with Tim Berners-Lee.
T
- Tag
- A tag augments a piece of information with certain ‘meta-information’ (information about the information). In HTML, XML and similar data formats tags are used to structure a document and add meaning to it. In modern web-based applications, users are allowed to tag information (webpages, articles, pictures, music) with certain keywords. These tags are then used by the system to classify the great amount of information. In this way users become active parts of a self-organizing information system. Tags are considered to be very ‘Web 2.0‘.
- TCP
- TCP stands for Transmission Control Protocol. It is one of the core protocols of the Internet. TCP allows for two programs on different hosts to set up a connection over which data can be reliably transported. It uses IP to communicate with the other endpoint. This combination is so ubiquitous on todays Internet that the two are usually referred to together as TCP/IP. Because IP packets can get lost or arrive out of order, TCP will keep track of the order in which packets arrive. It will request a retransmit when necessary, and place packets in order again before delivering them to the application.
- Tim Berners-Lee
- Together with Robert Cailiau Tim Berners-Lee invented the World Wide Web, while working at CERN. He later became chair of the W3C, and is actively involved in developing the semantic web.
U
- URL
- Uniform Resource Locator. A standard way to uniquely and uniformly designate a resource on the Internet, especially the World Wide Web. A URL for a web page starts with http:// followed by an identifier of the server containing the page (e.g. www.arnebrasseur.net), followed by a server-specific identifier of the exact resource. Later the concept has been generalized, so nowadays a URL is considered a special kind of URI.
- Usenet
- Is a distributed discussion system where users can post email-like messages to various newsgroups. Every newsgroup has a certain topic. Most of the newsgroups are unmoderated. Conceived in 1979 it predates the Web by a decade. Originally it wasn’t even part of the Internet, but was intended as an alternative to those excluded from the ARPANET. However most of Usenet traffic travels over the Internet nowadays. With the popularisation of the Internet, Usenet has experienced a big culture clash between the original scientific users, and the wave of new users during the 1990’s. Google has archived all messages since 1981. They are available over the Web under the name Google Groups.
W
- Web
- see World Wide Web
- Web 2.0
- Buzzword used to describe websites that incorporate important technological innovations. Mostly used to describe sites that are based on user generated content and folksonomies, and/or provide an interactive, often AJAX-based user interface. It should be noted that different authors mean different things, and that often a number of examples are given instead of actually explaining what is meant with the term.
- Webbrowser
- A computer program that can communicate with webservers to retrieve and display webpages. There is a wide range of webbrowsers available, both commercial (Opera, Internet Explorer, Safari) and public domain (Mozilla, Firefox, Camino, Flock, Konqueror, Epiphany). The first webbrowser was written by Tim Berners-Lee and only operated on the NextSTEP computer platform. The first graphical browser was Mosaic, developed at NCSA. The first company to develop a browser was Netscape with the Netscape Navigator. During the late 1990’s there was heavy competition between Netscape Navigator and Microsoft’s Internet explorer to become the dominant webbrowser. This period is known as the first browser war.
- Webpage
- Any document that can be viewed in a webbrowser. Most webpages are part of a greater website. The standard way to make a web site is to use HTML. A web page can be automatically generated by the server, for instance a page with search results (see also Server Side Scripting). It can also contain program code that is executed by the webbrowser viewing the page. This is known as Client Side Scripting.
- Webserver
- The term webserver can be used to refer to a machine connected to the Internet that serves webpages through the HTTP protocol, or it can refer to the program running on such a machine that accomplishes this task. Examples of such programs are the open-source (public domain) Apache, developed by the Apache Foundation, and IIS developed by Microsoft. The basic task of a webserver is to transmit a locally stored document to the computer that requested it. A more advanced use is to let the webserver execute a small program on each request, which will generate the document that has to be transmitted. This is known as server-side scripting.
- Website
- A collection of interrellated webpages, usually on the same host, with a common structure or goal is called a website.
- World Wide Web
- The World Wide Web, often abbreviated to ‘WWW’ or simply ‘The Web’, is a global distributed collection of interlinked information resources. These resources are made available through webservers, which are accessible via the HTTP protocol. A resource can be a static document, stored on the server and transmitted to whomever requests it, or they can be dynamic, generated on-the-fly when handling the request. Every resource that can be requested in this way can be uniquely identified by a URL, which is a special kind of URI. The Web is available over the Internet, which forms the underlying infrastructure that is also used to send emails, for instance.