Levels of specificity for selection of elements

Low:

Returns tag name of element.

Medium:

• If an element has a class, tag.class is returned.

• If a element doesn’t have a class, but has an ID, #id is returned.

• If none of the above, the above two steps are applied to the parent of the element. This maybe done upto 2 times.
  The selector then becomes: parent-selector child-selector

High:

• If element has an ID, #id is returned.

• If element has a class, its selector becomes tag.class and these two steps are applied to its parent. This is done only one time.
  The selector then becomes: parent-selector child-selector