5.       Trojan: A Trojan or Trojan horse does not replicate itself. However, it is a program that can cause harm to a computer. This harm might include data theft or provide a backdoor to your computer or computer data. A Trojan can significantly slow a computer and is one of the most common signs that a Trojan exists. Trojans also do not insert themselves into other programs or files. Experts claim that over 80% of malware are Trojans. Malware creates a necessity for anti-malware software. Before running any program or email attachment, be sure the source can be trusted. Most anti-malware programs are able to scan individual files. This can be good insurance, but it’s important to keep your anti-malware software up to date. Be sure you’re getting regular updates.