Computer security can be defined as protecting computer and its data from any loss or illegal access from range of other users. Normally file viruses and program viruses are downloaded from internet. When you tend to download a file from internet, make sure to download from trusty sites. Most of sites infect your computer by injecting virus in your system.
If you are downloading any program from internet like an antivirus program or any file attachment from your mail inbox, you must select “Save” option if you are downloading from any unknown site offering free software downloading. Always scan the file before downloading the program and opening it. Use updated version of anti-virus program if you are internet user to protect your computer from harms.