Spyware is a type of malware

Malware

Malware, short for malicious software, consists of programming that is designed to disrupt or deny operation, gather information that leads to loss of privacy or exploitation, or gain unauthorized access to system resources, or that otherwise exhibits abusive behavior...

 that can be installed on computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

s, and which collects small pieces of information about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect. Typically, spyware is secretly installed on the user's personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer

Public computer

A public computer is any of various computers available in public areas. Some places where public computers may be available are libraries, schools, or facilities run by government....

 on purpose in order to secretly monitor other users.

While the term spyware suggests software that secretly monitors the user's computing, the functions of spyware extend well beyond simple monitoring.