An antivirus software program detects, removes, and prevents the entry of computer viruses, trojan horses, and other malware. There are various types and brands of antivirus programs and all these use different strategies for the function. The malware detection pattern and removal methods differ from program to program. So it is always important to install the program suiting your operating system and browsing habits. Some antivirus programs have a drawback in a way that they lower the system performance. When buying an antivirus product, look for the price, the performance, and its ranking. It is good if you do a little bit of research before opting for one.