What types of committees are there in Congress?

Students of the US Congress generally say that there are
either 3 or 4 kinds of committees in Congress.

The most
important and most common of these is called the "Standing Committee."  These are
committees (in both the Senate and the House) that are permanent and which have
permanent jurisdictions and duties.  These are the committees like Defense and
Judiciary.  These committees have subcommittees as
well.

The second kind of committee is a select or special
committee.  This kind of committee is set up on a temporary basis for some particular
task.

Third, there are joint committees.  These are
permanent, but are made up of members of both houses.  They are generally not charged
with legislative duties -- they are more just for administrative stuff like overseeing
the Government Printing Office.

Finally, there are
conference committees.  These are a special kind of joint committee.  They are appointed
on a temporary basis whenever the two houses pass different versions of the same law. 
When this happens, the conference committee has to iron out the differences and produce
one identical version of the bill.