1.virus is a computer program
2.copies itself
3.may do other damage
4.may modify system
5.may have obvious effect
virus symptoms
1.program takes longer than normal to load
2.less memory than usually available
3.file extensions or file attributes change
4.files constantly get corrupted
5.noticeable reduction in disk space
Best antivirus software
kaspersky,bit defender,avira, f-secure,norton,AVG
