A powerful firewall. As they have claimed "Comodo has a mission: That is to make sure that all PC users are secure as they transact on the net. We make our money off doing business with merchants so we don't look at PC security as our bread and butter. We look at it as our obligation, since we are a leading Certification Authority, committed to ensuring trustworthy transactions on the net. Our "trust" initiative also makes available free some tools to avoid leading threats such as phishing attacks. The free tools include: the ability to authenticate web identities in real time, PC vulnerability scanning, free email certificates for secure email encryption, secure backup for backing up files on your PC and iVault for password management and launching secured internet sessions.", it's absolutely free.