Malware can be categorized into different types based on the damage it causes to the system. Malware does not necessarily use a single method to cause damage; it can employ multiple ways. We will look into some known malware types. The following are some categories:

• Backdoor
• Downloader
• Virus or file infector
• Worm
• Botnet
• Remote Access Tool (RAT)
• Hacktool
• Keylogger and password stealer
• Banking malware
• POS malware
• Ransomware
• Exploit and exploit kits

To be clear, malware can act as a backdoor as well a password stealer or can be a combination of any of them. Some of the definitions are simple enough to understand in one line while others need some detailed explanation.