Keystroke logging software is just what it sounds like: it keeps track of everything you type on your computer keyboard. It is used by cybercriminals and regular people alike.  Parents use it to spy on children, spouses spy on each other, and employers monitor employees. And yes, hackers may try to install keystroke logging software on a personal computer if they can gain access.

A firewall and up-to-date anti-malware software offer some protection, and you can get anti-keystroke logging software as well.

You can also keep hackers from finding what they're looking for: passwords and credit card numbers you enter at e-commerce sites. There is software that stores passwords and credit-card numbers and enters them automatically. Or, take advantage of the fact that keystroke loggers don't track your mouse. For instance, enter the first three letters of your password, then enter three incorrect letters, then use your mouse to select those and type the correct ones over them (without pressing "delete"). This causes your password to appear three characters longer than it really is.