There are many different types of viruses for example.

• Trojans
• Viruses
• Worms
• Adware
  
• Spyware
• Spam
• Bot
• Ransomware 
  Ransomware is a type of malware that can alter the normal operation of your machine. It encrypts the data and prevents you from using your computer partially or wholly. Ransomware programs also display warning messages asking for money to get your device back to normal working condition.
  
  Adware are used to display advertisements on your computer’s desktop or inside individual programs. They generally come attached with free-to-use software. They are the primary source of revenue for the developers of those software programs.