Few questions

Ok, so I listed out all the table using '\l'.  3 were
displayed:

  List of databases
   Name    |  Owner
-----------+----------
 template0 | postgres
 template1 | postgres
 test      | postgres
(3 rows)

However, when I did

\d test

It came back with the error:

Did not find any relation named "test".

Why?  Is the table not really there?  If that's the case,
why is it showing up with '\l'?

Also, I was reading through the documentation and I just
want to be clear what a "tuple" is.  Is it a row of data or
anything else in the singular that is returned by a query?

thnx,
Chris