A
worldwide collection of
hyperlinked
text,
images, and other types of
computerized data.
The web is a client-server system in which there are many servers all over the internet, which provide documents to the clients, web browsers which users use to access the web.
The fundamental type of document is a text file written in HTML (Hyper Text Markup Language). HTML is a markup language in which the text is interspersed with symbolic codes that represent formatting, document structure, and hyperlinks. These documents are normally accessed by a system called HTTP (Hyper Text Transfer Protocol), which is somewhat similar to FTP in that a client asks a server for one or more documents, and the server sends them, or gives an error if it is unable to.
Hyperlinks are simply references to other documents in the web. These references have a common form, called a URL (Uniform Resource Locator), which is designed to make it possible to reference any network-accessible document, including those accessible by methods other than HTTP. URLs can specify older methods of accessing documents (such as FTP) which predate the web, and are extensible to handle access methods not yet dreamed of.
Thus, the web can be thought of as encompassing essentially all forms of communication over the internet. Though most of the networking not based on HTML documents transported over HTTP are often not considered to be part of the web, most of them can be accessed from the web.