Bug Bounty Hunting — Complete Guide (Part-24)

A web browser connects to a web server using HTTP, a protocol designed to efficiently handle hypertext and hypermedia documents. These documents can include text, images, audio, and video. Web pages are primarily created in HTML and typically saved with a .html or .html extension. HTML structures web content like text, images, and media, and enables links to other pages across the internet. When you click on such a link, your browser retrieves and displays the linked page.

The web uses a universal addressing system, allowing links to various internet services such as web pages, email, file transfers, and multimedia streaming. This expansive network ensures that a web browser can access a vast array of information and services online. For instance, browsing a news website enables access to articles, images, and videos related to current events.

The internet uses Uniform Resource Locators (URLs) to pinpoint resources like files and services. A URL typically includes details such as the host, server port, and specific file stored on that host. URLs are vital for browsers to fetch information and for HTML to link to other resources. A complete URL usually follows this structure:

scheme://server:port/pathname. The scheme defines the type of service and the protocol to be used. For instance, “http” indicates the Hypertext Transfer Protocol used by the web. Another example is “ftp,” which signifies the File Transfer Protocol for accessing files on servers like ftp://ftp.example.com/docs/. The “file” scheme points to local files, such as file:///home/user/document.txt. URLs can also direct email using “mailto” or enable remote login via “telnet.” For instance, mailto:example@email.com directs emails, while telnet://example.com connects to a remote host. Each URL component serves a specific purpose: the server identifies the host and server program, and a port number is optional if the default isn’t used (e.g., 21 for FTP, 80 for HTTP). The pathname following the server typically denotes a file or directory. If a pathname ends with ‘/’, it signifies a directory rather than a file.

File types are indicated by suffixes like .html or .jpg. URLs within HTML documents can link to files on the same server by specifying just the pathname. For instance, /images/photo.jpg refers to an image in the root directory. Using relative URLs, like file_xyz.html, simplifies linking within a website, especially when referring to files relative to the current page’s location.

You can enter a URL directly into your browser’s address bar to access any web document, directory, or service. If the URL points to a directory, the web server typically displays an index file like index.html, or a list of filenames if no index file is found. The web hosts an immense amount of valuable information, although finding specific content can be challenging due to its decentralized nature.

Thankfully, search engines exist to compile and index web content, making it easier to locate information. These search engines continually update their databases and are invaluable tools for information retrieval. When new websites are created, they often submit their URLs to popular search engines like Google to ensure inclusion in search results.