The concept of JQuery selector is from CSS selector

Borrowing from CSS 1–3, and then adding its own, jQuery offers a powerful set of tools for matching a set of elements in a document.

http://api.jquery.com/category/selectors/

CSS Selector:

http://www.w3schools.com/css/css_id_class.asp

CSS 2 Selector reference

http://www.w3.org/TR/CSS2/selector.html