Programs in the first category, which are sometimes called “snoopware”, are typically stand-alone programs installed intentionally by one user onto a computer used by others. Some capture all keystrokes and record periodic screen shots, while others are more focused, just grabbing websites visited or suspected passwords.
These programs have legal uses (e.g. for certain narrow kinds of employee monitoring) as well as many clearly illegal ones. The best known spyware programs are Trojans which are mostly used by hackers.
They enable them to capture important data from victims’ computer – keystrokes, e-mail addresses, screenshots, passwords, download files…
