What Does Browser Helper Object (BHO) Mean?

A Browser Helper Object (BHO) is a DLL module designed by Microsoft to allow developers to create plug-ins for its Internet Explorer browser. BHOs can display content that was not originally written in HTML, such as a PDF file, or it can allow developers to add toolbars to the browser. BHOs are supported in Internet Explorer version 4 and up.

Techopedia Explains Browser Helper Object (BHO)

The Browser Helper Object was created by Microsoft in 1997 to make it easy for developers to create plug-ins for Internet Explorer and Windows Explorer. They are implemented as DLL modules.