http:/ / www.pcmag.com/ article2/ 0,4149,1158997,00.asp
BHOs are a special type of add-in for Internet Explorer 4.0 or higher. Poorly written BHOs can cause Explorer to crash. Windows doesn't provide a way to see the BHOs on your system, and some BHOs (for example, adware) operate invisibly and don't have a user interface. BHO Cop can solve these problems.
