Online threats are malware programs that can target you when you’re using the Internet. It is designed to affect the computer of the victim. Trojan horse, worms, virus, spyware are some of the different types of online threats. A Trojan horse, or Trojan, is a type of malicious code or software that looks legitimate but can take control of your computer. A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Many viruses are harmful and can destroy data, slow down system resources, and log keystrokes.