In a user-defined installation or a change installation, the following installation modules can be selected, added or removed.

Avira Free Antivirus
This module contains all components required for successful installation of your Avira product.

Real-Time Protection
The Avira Real-Time Protection runs in the background. It monitors and repairs, if possible, files during operations such as open, write and copy in on-access mode. Whenever a user carries out a file operation (e.g. load document, execute, copy), the Avira product automatically scans the file. Renaming a file does not trigger a scan by Avira Real-Time Protection.

Rootkits Protection
Avira Rootkits Protection checks whether software is already installed on your computer that can no longer be detected with conventional methods of malware protection after penetrating the computer system.

Web Protection (for Avira Free Antivirus users, only in combination with the Avira SearchFree Toolbar)
When surfing the Internet, you are using your web browser to request data from a web server. The data transferred from the web server (HTML files, script and image files, Flash files, video and music streams, etc.) will normally be moved directly into the browser cache for display in the web browser, meaning that an on-access scan as performed by Avira Real-Time Protection is not possible. This could allow viruses and unwanted programs to access your computer system. Web Protection is what is known as an HTTP proxy which monitors the ports used for data transfer (80, 8080, 3128) and scans the transferred data for viruses and unwanted programs. Depending on the configuration, the program may process the affected files automatically or prompt the user for a specific action.

Shell Extension
The Shell Extension generates an entry Scan selected files with Avira in the context menu of the Windows Explorer (right-hand mouse button). With this entry you can directly scan files or directories.

Online Manual of Avira