Jquery selectors are cool

http://www.codylindley.com/jqueryselectors/
These are very useful for web programming with javascript Jquery.
You can use these kinds of Jquery selectors to loop through all the elements that match many different kinds of selectors such as class, id, or just first or last or nth or parent or child.
So you can actually do things not just to children but to parents of an element too.

I have used this kind of selector to get the id or other information from the first td in each row of a table. And to change the background color of the rows as you pass through them too.