jQuery – count number of rows in a table

How do I count the number of tr elements within a table using jquery. Sorry, I sense this might be basic but i’ve been banging my head against it.

I know there is a similar thread, but I just want the total rows.
http://stackoverflow.com/questions/613024/count-number-of-table-rows-between-two-specific-rows-with-jquery

jQuery – count number of rows in a table