ANSI ,TIA , BICSI ...etc, what are the relations ?

Note : I'm talking about structured cabling

I'm a little bit confused, between all these organizations. I know that ANSI is the American standards. And I know that TIA is having standards for structured cabling and other things. And also I know that BICSI is providing training and they are have the IT experts and they are providing best practices and guidelines for the same.

But what I'm confused about it are (for TIA, BICSI) :

1)are they are providing standards or best practices, training.. Etc, only?

2) are they are contributer with ANSI, or what? Since I see for ex ANSI/BICSI 00x standards?? What does that mean? Does that mean ANSI, had an agreement with bicsi to make a standards?

3) how many communication organization standards are there in the USA? Only ANSI?

4) what is ANSI doing for communication standards? Are they are the one who write their own communication standards? Since 99% of the SCS, I see ANSI/TIA/EIA. Not ANSI alone.

5) what does ANSI/TIA/EIA XXX or ANSI XXX means?

Thanks alot and sorry for my bad English :)

Kindly fill the gap for me..