IntroductionComputers are becoming more and more important machines and the uses of computer are becoming variety in our life. The reason why they use computer for different purposes is that people look for the computer specifications they need. To meet the needs of people, computers are developing rapidly, however, with the growth of the use of computers, the computer is not the only one to develop, the Internet is developing rapidly. The Internet is essential in our lives now. Over billions of people around the world use the Internet to communicate with each other or get the information they need faster without any limitation of time and place. This makes the quality of human life convenient and rapidly improves the network and Internet. However, the development of the Internet also brings disadvantages, usually computer viruses known as malicious programs. Computer viruses are spreading rapidly across the Internet and now represent one of the main threats to the contemporary information society. Viruses can corrupt computer data, steal private information, or even control your computer. To protect yourself from viruses, antivirus software was invented and is being developed by many companies lately. Antivirus software is the program that has some unique methods to detect and remove malicious programs. Computer Viruses There are hundreds of thousands of viruses in the world, and they are usually designed for different purposes or objectives. Most computer viruses written in the early and mid-1980s were limited to self-reproduction and did not have a specific damage routine built into the code, but after more and more programmers began to familiarize themselves with virus programming, they created virus capable of modifying data or even destroying it on the infected computer. A computer...... middle of paper...... computer and various features to help additional protections. But most of them use the same basic detection methods such as real-time protection, signature-based detection, heuristic detection and rootkit detection. In antivirus industries, the most significant work is to classify known viruses based on their activities, even a single malicious program has several malicious activities and propagation routines. References http://www.avast.com/en-nz/compare-antivirus http://en.wikipedia.org/wiki/Computer_virus virus history http://csrc.nist.gov/publications/nistir/threats/ subsubsection3_3_1_1.html Heuristic Virus http://www.pctools.com/security-news /heuristic-virus-definition/ Rootkit http://en.wikipedia.org/wiki/Rootkit Zenny Zelster http://blog.zeltser.com /post/1256199682/what-is-cloud-anti-virus Federick B, Cohenhttp://en.wikipedia.org/wiki/Fred_Cohen