avast! 4 Professional Edition is a collection of award winning, high-end technologies that work in perfect synergy, having one common goal: to protect your system and valuable data against computer viruses. It represents a best-in-class solution for any Windows-based workstation. 

avast! Home Edition is now free of charge for HOME users for NON-COMMERCIAL use. You can find more information here. If you are not a home user, or you use your computer for profit, the avast! Home Edition is not licensed for such use, and you are asked to use the commercial version - avast! Professional Edition.

To use the Home Edition, you should register it, however, after initial installation you have 60 days to trial the product (as with all avast! antivirus products) before you must complete registration. The registration process is very easy, and will take you only a couple of minutes.

All the setup packages are in the form of self-extracting executables and are digitally signed by ALWIL Software.