As a precursor to this discussion, let me clarify that this thread is not supposed to be about or intended to start a pissing contest and flaming war between the various AV fanboys, rather it is a serious question grounded in curiosity and as such the discussion should focus simply on the question posed. That being said, lets continue onto the subject matter itself. . . Clearly NOD32 and KAV are the long reigning kings of AVs, they are the big boys on the block, not of course in regards to their user base, but in terms of their longstanding effectiveness. Over time, these two AVs emerge and prevail as the two most effective, the first choice for many computer security enthusiasts. So my question is, why are there numerous 3rd party AVs that license and incorporate the KAV engine, but none (that I know of) that do so with the NOD32 engine? Is it because ESET refuses to license it out? Or because there are no interested companies vying for such a license? Or something else altogether?