Brian Cryer's Glossary of IT Terms with Links

Adware

Adware

A collective name for software which displays advertising banners or pop-ups while the user is using the application. Typically the software may be free at the point of use and is supported by the revenue generated from displaying advertisements.

Sometimes the advertisements are independent of the application the user originally installed.

Adware can be distracting and sometimes annoying, but other than taking up bandwidth (because the application will typically download new adverts) it is not in itself harmful.