Antivirus is a software which is used to prevent, detect, and remove spyware, malware and many types of viruses. Without antivirus software, viruses will infect your computer. Viruses infect other files it can be disguised as attachments of funny images, greeting cards, or audio and video files., Worms make copies of themselves, Trojans perform malicious actions but do not spread. Antivirus searches a hard disk for viruses and removes any that are found. So, installing antivirus software is a must software to protect their computer. Some viruses just replicate themselves, but some can cause serious problems to user. You can help protect your computer against viruses by using antivirus software. Most antivirus software programs can usefully identify common and uncommon malware applications that have been unwittingly installed on a computer system. User education is as important as anti-virus software; simply training users in safe computing practices, such as not downloading and executing unknown programs from the Internet, would slow the spread of viruses, without the need of anti-virus software. Antivirus software can use to identify malware by Signature based detection, heuristic analysis, Rootkit detection. some time Antivirus software can degrade computer performance and speed. If you running multiple antivirus programs this can also be degrade the performance of the computer. you need to have an antivirus program which has little effect to computer performance which runs in background of computer system. Antivirus software is widely used for all levels of users including home, office, small and medium business. An antivirus software can easily stop unauthorized access to your computer system when performing many of your usual online activities. You can get directory submission software simply from some websites, you can also find the best directory submission by directory submission software. There are a large number of antivirus software programs available Some are free to use and others will cost you a specific fee to access thier features. Remember to update your antivirus software regularly. If you updated your antivirus software regularly you have good performance of your PC. It might be difficult to download tools or update your computer if your computer has a virus. In this case, you can try one of the following options, You can perform updates using the Check for Updates option within the menu that opens after right mouse button clicking over the antivirus icon located on the system tray. You can also use free scans generally offered by most antivirus software suppliers. It have scanning capability of the entire computer, critical areas only, local disks, folders or files.