8. Spyware. Several free programs online come bundled with spyware that monitor your internet activities in clandestine fashion. This includes key-loggers, which record your every keystroke, which people use to gather your personal information, with a possible aim of identity theft. Anti-virus software won't be able to spot it because it will look like something you chose to install.

 

9. Adware. It is similar to spyware but comes in the form of advertising banners that display while the program is running, all the while containing some spyware code used to gather personal information.

 

10. Viruses and worms. They usually disguise themselves as seemingly harmless email attachments. Speaking of which, always treat your email attachments with doubt. If it's unfamiliar, junk it immediately. They may do damage to your security system and leave you powerless in the hands of a hacker looking to steal identities.

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