In addition, many let you view the HTML version of the document and examine the actual HTML code used to create it. A Web browser receives raw HTML or other data and formats the material or starts another application such as a video player. In most cases you need to configure, or verify the configuration of, Helper applications from within the Web browser itself. Web clients are also responsible for interacting with non-Web servers such as Gopher or FTP directly and they create a virtual HTML document while doing so. The Web consists of documents and links.
Indexes are special documents which, rather than being read, can be searched.
The result of such a search is another virtual document containing links to the documents found. The browser uses the URL you enter and the HTTP protocol to request a keyword search by a remote information server. The Web contains documents in many formats. All documents, whether real, virtual, or indexes, look similar to the reader and are contained within the same addressing scheme. There are a lot of browsers for the World Wide Web.