A Trojan-horse code (aka "Trojan") or Virus is usually malicious code that can infect your computer and is something everyone should be aware of.
Trojan vs. Virus
A trojan can infect your computer through any odd executable file you might have downloaded (for whatever reason), and these days even from an infected media file. This means the user has to actively run or load something to infect their computer. Most trojans are activated through some form of Social engineering scheme.
A virus can infect a computer program by replicating itself sometimes without direct user interaction, but other times it works similarly to a trojan where the infection is spread via user interaction with an infected program.
Once your computer is infected you run the risk that the code is sending your account data to the creator of the code as you type it or later in some preset upload, who might then steal your account information and claim it as his own.
Things to do
- Get a Virus Scanner
- Keep your virus definitions software up to date.
- Do not open or click on suspicious files.
- Do not download files from anyone you do not trust.
- Do not accept files from untrusted people in your MSN, ICQ, Yahoo or other Instant messenger list.
- Keep spyware away from your computer
- Do not use applications such as Kazaa or other mass file sharing tools. Shared files are commonly infected with virusses, and the application itself will also often try to unload a bucket load of Spyware onto your computer.
- Enable your Windows Firewall or get a third-party one.