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Fragment ID (Optional): A fragment identifier is used to identify a portion of the document. For example, if you
click on a hyperlink in the left panel of the webpage, the corresponding content is displayed (see Fig 7.5)
Fig 7.5: Result of clicking the portion on the left panel.
When you request a resource from the Internet, your browser acts as a client. An application program called resolver
(invoked by the operating system) looks for the web page in the local cache of your machine. If not found, your Internet
Service Provider's resolver (ISP) looks for it in its local cache. If the required IP address is not found in the local
cache of the ISP, the resolver will search for it in the public DNS (Domain Name System). Once the IP address of the
docs.python.org is resolved (199.232.20.223), the HTTP request for the requested web page from the client goes to
the server (IP Address: 199.232.20.223).
• The browser's function that examines the HTML file is called a parser. The parser interprets the HTML document
comprising several pieces: the content, structure, and URLs. The structure of an HTML file is described in section 7.1.4.
• The browser fetches the linked resources, such as media content (images and videos), and cascading style sheets
(CSS) and determines how the web page appears on the device (font, position, etc.). A JavaScript executing on the
browser determines the web page's behaviour (action performed on click of a button) when loaded.
• The browser then builds and renders (makes visible) the document on the browser screen.
Request
Response
Server
CSS
Client HTML
JavaScript
7.1.4 HTML
HyperText Markup Language (HTML) is used to design web pages. Developed in the year 1990, HTML is used for
specifying the content and layout of web pages. It is a case insensitive language. It makes use of a set of predefined
tags. Earlier, web pages developed using HTML language were static.
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