Plug-ins programs can easily be installed as a part of the browser to extend the basic functions originally built into the browser. A plug-in is recognized automatically by the browser and its function is integrated into the main HTML file that is being presented. When a browser finds a file type it does not directly support, it launches the plug-in application that retrieves all the multimedia files from a server. Plug-ins retrieve a small portion of a file at one time and then store the data in the local disk cache. Therefore, a continuous stream of data is built to eliminate a transfer delay, which is referred to as streaming. Some of the different types of plug-ins are Real Player, Apple Quick Time, Adobe Acrobat Reader, and Macromedia Flash Player.

Installing plug-ins
There are two ways to install plug-ins. There are On-line installation and Offline installation. On-line installation occurs with your web browser open. There are many browser plug-in installation files that support on-line installation, but many are installed offline. Offline installation occurs when the user downloads the plug-in file. The user then has to close the browser and start the installation file, and restart the computer. When doing any type of installation on the computer it is very important that the user carefully reads the installation instructions before the downloading process takes place.

Examples of plug-ins
There are many plug-ins and viewers that can be installed for the user's convenience. A few common ones are Real Player for PC's, Apple Real Networks, Adobe Acrobat Reader, and Macromedia Flash Player. Real Player is known for developing the streaming format and introduced Real Audio and the Real Video then after. They both have combined into one application that many users find convenient for their PC called Real Player. Real Player is used to display the name of the music or video file and the time that remains on the track.

Apple Quick Time works optimally with Macintosh computers but also works on PC's. Quick Time is used to store video and audio files in digital format. The Quick-Time plug-in works with Quick-Time movies and others that can use the fast start feature that allows the movie to begin before it has completely downloaded.

Adobe Acrobat created the Portable Document Format (PDF), a file format that can be created and read on any computer, regardless of operating system. Because PDF files are highly compressed they take a short time to download. Another benefit of PDF files is the ability to maintain all formatting information originally created.