Blurry photographs are an extremely common problem among photographers of all skill levels. However, there is no one cause for all of these blurry images. Rather, blurry images are caused by several different common errors and situations.
depth of field is too shallow for the subject. These focus issues have very simple solutions. However, these solutions can vary a bit depending the type of camera you have. If you have a SLR type camera you do have a few more options for correcting focus than point and shoot users have. Point and shoot users do still have ways to work around focusing issues as well.
Shutter speed blur has a different look than does unstable support. Take a look at these images to see what different types of blurring looks like.