Whatever happened to the Second Party?

For a long time now, I have been using First Party software.  That is to say, software developed by the hardware manufacturer.  I have also been using Third Party software - that is, software developed by someone else.

Third-party hardware as well - accessories you add on to your car, computer, what have you.  There certainly do seem to be some parties going on here.  Are they related to the political parties?

Now, my big question.  In order to be the third party, you have to first have a second party (read that sentence several times!!).  So, who is this phantom Second Party?  Do they serve drinks?  What exactly do they make, or do for that matter?  I have never seen nor heard of a product made by them.  Really, what's the deal?  If anyone knows of this mysterious group, I will pay good money* for:

• Their address
• Some contact names
• A list of products they make
• Their Twitter, Facebook, or other social networking page link

* When I say "good money", I mean my definition of good money.  Money I think is good.  That may or may not be legal tender.