Malware is any malicious software that can cause harm to any computing system or network. A piece of malware may have multiple functions, such as wiping data from a hard drive, capturing screenshots of the victim's monitor, or even creating a backdoor. 

Some types of malware include:

• Viruses
• Crypto-malware, ransomware
• Worms
• Trojan Horse
• Rootkit
• Keylogger
• Adware/spyware
• Botnet