ActiveX: ActiveX is a set of technologies from Microsoft that enables interactive content for the World Wide Web. Unfortunately, lax default ActiveX security settings in Internet Explorer can allow any webpage to secretly install ActiveX controls automatically. Since these ActiveX controls can do almost anything (including installing software, such as spyware or other potentially unwanted software), many consider them a significant security threat. SpywareBlaster uses kill bits to prevent webpages from installing spyware or other potentially unwanted ActiveX components, and also to block many of them from running, if they are already installed.
BHO: Browser Helper Objects are small programs that extend the functionality of Microsoft Internet Explorer. Many toolbars shown in Internet Explorer are BHOs. Spyware and browser hijackers frequently use BHOs to integrate themselves with Internet Explorer, and to display advertisements, capture data, etc. BHOs are often installed by small ActiveX-based files.
Browser Hijacker: Browser Hijackers are programs that attempt to alter homepage, searchpage and/or other browser settings. Some also install additional files that change these settings back on every restart (if you should try to revert to your old settings). Browser Hijackers may be installed by ActiveX controls on webpages.
Browser Pages: These are settings on your system that refer to webpages that your browser may use for various functions (search, homepage, etc.).
Hosts File: The Hosts file is a lot like an address book. When you type an address into your browser (ex., your computer typically connects to your ISP's (Internet Service Provider's) DNS service to translate the easy to remember website address into a numeric address (otherwise known as an IP address). If this information exists in the Hosts file instead, your computer will use it (your computer assumes this data is correct).
Spyware: Definition of spyware "Spyware is software or hardware installed on a computer without the user's knowledge which gathers information about that user for later retrieval by whomever controls the spyware." Generally, much so-called "adware" can be considered a form of spyware (however it typically monitors you for only one purpose: delivering targeted ads).