Avast! Free Antivirus is the freeware version of the Avast! antivirus software available to Microsoft Windows and Linux users, while Avast! Pro Antivirus is offered to businesses and users who want additional features. Priority updates are delivered automatically using PUSH update technology in Avast! Pro Antivirus. Avast! Pro Antivirus also has a command line scanner and a script blocker; however, in version 6, the script blocker is available to users of the free version.
Avast! Antivirus is a widely used antivirus program, with 130 million users worldwide as of September 2010.
- Antivirus kernel based on certified antivirus engine.
- Resident protection comprising individual modules or "shields", each of which can be individually configured or disabled:
- File System Shield — Real-time protection against viruses and other malware threats. Scans files as they run on your computer to keep viruses from being able to execute.
- Mail Shield — Scans messages and attachments in E-mail/Microsoft Outlook/Exchange for viruses.
- Web Shield — HTTP protection (local transparent proxy). Version 4.8 also allows the blocking of URLs. Scans URLs and incoming data for viruses, and aborts connections to the site if one is found.
- P2P Shield — Scans P2Pfiles from file share programs.
- IM Shield — Instant Messaging protection. (Scanning of files transferred through instant messaging applications)
- Script Shield — Scans webpages for malicious scripts, and disables them from infecting your computer, though they can still be used. (for example, a clickable button)
- Network Shield — Basic protection against well-known network worms. Acts as an Intrusion Detection System.
- Behavior Shield — Reports suspicious behavior by analyzing the behavior of programs
- Anti-spyware capabilities
- Anti-rootkit capabilities
- Self-Protection — Prevents malware from terminating avast! processes and damaging avast! files.
- Automatic incremental updates — Updates of both the program and the virus database which is used to identify potential threats — Avast! updates its virus definitions on a regular basis (sometimes multiple updates daily) and this process is automated by default.
- Audible alarms — Vocal warnings and notices such as "Caution, a virus has been detected!" and "Virus database has been updated."
- Boot-time scan — Users can schedule a boot-time scan to remove infections that load during Windows startup.
- Virus Chest — Quarantine; folder where infected files can be stored. The virus chest also stores vital system files to protect them from damage by malware. Users can also add their own files to the virus chest. Once in the chest, a file cannot be executed; double-clicking the file will instead display information about the file.
- SafeZone — SafeZone is special web browser in avast! Pro Antivirus 6.x and avast! Internet Security 6.x, which allows users to browse the web in a private, secure environment, invisible to the rest of the users' system.
- WebRep browser plugin — WebRep is a community-based website reputation tool implemented in version 6.0 of Avast! Antivirus.