When I first started to take photography seriously over 10 years ago, mastering depth of field was high on my priority list. Shooting with a narrow depth of field involves setting your camera lens to the widest possible setting and then focusing on one particular part of the frame. The stark contrast between in and out of focus portions of the frame concentrating around the subject and relative distance to other things in the frame creates a wonderful, visually appealing, texture enriched image. In my mind, being able to properly produce a shot with the right depth of field makes the difference between a snapshot and a photograph. Here's 13 excellent examples of narrow depth of field to give you some inspiration.
Adobe Apple Canon Casio Cokin Fujifilm Hasselblad Holga Kenko Kodak Leica Lensbaby Lytro Mamiya Nikon Olympus Panasonic Pentax Phase One Polaroid Profoto Ricoh Samsung Samyang Sigma Singh-Ray Sony Tamron Tiffen Tokina Vivitar Yongnuo Zeiss Zenit