http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field. This tutorial is designed to give a better intuitive and technical understanding for photography, and provides a depth of field calculator to show how it varies with your camera settings.

The buildingds behind her is a great example of deph of field because they are big and they slowly get smaller and smaller until you cant see no more.

I really like this photo because the lighting and deph of field really brings out alot of detail in the photo and it is very cleverly took.

The red lipstick on the girl really show out her face because that is the only bright thing in the picture.