Spyware is a type of malicious software that stealthily observes the activities of a computer user without their consent. It can cause harm to computers by stealing sensitive information, slowing down their performance or even crashing them. There are several synonyms for spyware. Malware is a generic term used to describe any harmful software, and spyware falls under its umbrella. Adware is another type of malicious software that displays unwanted advertisements and can sometimes collect user data. Keyloggers record all keystrokes made by a user, including passwords and sensitive information. Finally, Trojans are harmful programs that disguise themselves as useful software or files to trick users into downloading them. It's important to secure your computer against these threats by using antivirus software and being cautious when downloading files.