A computer worm is one of the most common types of malware. It’s similar to a virus, but it spreads differently: worms have the ability to spread independently and self-replicate automatically by exploiting operating system vulnerabilities, while viruses rely on human activity in order to spread. It’s usually “caught” via mass emails that contain infected attachments. Worms may also include “payloads” that damage host computers, commonly designed to steal data, delete files, send documents via email, or install backdoors.