• Trojan: software that user installs, it looks like a gift but in the backdoor, it’s doing something else.
• Virus: software that the user has interact with it to propagate to other hosts or other programs within a system.
• Worm: self-propagating viruses. if it’s on your PC, it looks for more vulnerabilities and expand on its own without user interaction. consumes resources (memory and processing)
• Polymorphic: (Poli -> Many) it appears different every time it activates, needs anti-malware/virus software that looking for a specific signature or pattern, if it’s changing every single time it executes, that’s hard to catch.
• Armored. built in with structure that it’s hard to reverse engineer to check how it was created. 
• Bot: little agent that runs on a computer. which can take instructions and do those things
• Spyware: kind of malware that’s essentially looking at everything you’re doing, or can identify where you’re going and sends to a collection site. Spyware will open a connection, and collect information such as my browsing habits, and other data, and then send it to a collection site.
• Crypto-Malware:  pop up message that says “congratulations”. All your data is encrypted and you don’t have the key to decrypt it. Asking for money.
• Rootkit: give you limited access to your systems, so hard to detect unless you have specific software that’s looking for that underlying rootkit. 
• Botnet: Bot installed on a ton of computers then a hacker with a command communicates with them and run them to activate something malicious.
• Ransomware: malware that holds your system and/or data hostage. Data is held hostage until you pay the ransom. spreads via phishing attacks

Useful links

• Download Anti Malware Test file.
• Scan it.
• Check the total amount of malware and potentially unwanted applications over time.