Avast! — антивирусное программное обеспечение, которое может найти вирусы на жестком диске ПК, в его памяти, в загрузочных секторах и т.д. Поддерживается поиск вирусов в письмах, имеется блокиратор скриптов. Вирусная база постоянно обновляется и может быть скачана через Интернет. Avast! обладает простым и понятным интерфейсом с поддержкой скинов. Выпускается в двух версиях – Home Edition (бесплатная для частного пользования) и Professional Edition (платная для организаций).

Version 4.8.1195 (May 12, 2008)
- solved incompatibility of the avast self protection module and the System Restore feature (Windows XP/Vista)
- solved keyboard/mouse lags in some games (e.g. World of Warcraft)
- "Quick" scan now quick again (in the previous version, it was usually slower than "Normal" scan)
- fixed slow resuming from hibernation (on certain systems)
- improved stability of aswSP.sys kernel driver
- fixed deleting of infected files in some nested archives
- shell extension: under Windows Vista, shortcut targets are now correctly scanned
- boot-time scanner now correctly displays warning messages about corrupted archives
- improved scanning speed in the Simple user interface
- improved handling of scan exceptions
- self protection: improved detection of changes in the INI file
- start of the "avast! Mail Scanner" service should now be fast again
- fixed a problem with avast being installed in a directory with name containing non-Latin characters
- fixed entering of the license key (didn't work in certain configurations)
- improved detection/healing of MBR rootkits
- avast can now correctly handle the case when the INI file is missing/corrupted
- the "Disable startup rootkit scan" option on the Troubleshooting page now effective
- P2P Shield: added support for Azureus Vuze and Qtrax
- taskbar messages from Internet Mail should now correctly handle most common character encodings
- fixed problems with the boot-time scanner on FAT[32] partitions
- small improvements in some unpackers (WinExec, RAR, CHM)
- fixed the message announcing the license key going to expire soon
- on 64-bit Windows, avast now detects both 32-bit and 64-bit version of the WHS connector
- the avast Home / Pro Edition comparison window is now correctly displayed even under Windows 9x