Adware:Adware (or spyware) is a small program that is designed to show advertisements (in various form and degrees of intrusiveness) on your computer. It often reports personal information back to its owners. As a result your sense of privacy can be violated.
Trojan.BHO.ab is a Trojan that secretly embeds itself into your web browser as a BHO (Browser Helper Object). Once inside your system, Trojan.BHO.ab will download and display large amounts of advertisements and will redirect your browser to certain unsolicited web sites.
Technical details (How to remove Trojan.BHO.ab(pop up))