Most people use the appliances in their homes without realizing how dangerous they can be if they are not maintained on a regular basis. Your dryer can be a fire hazard because the lint from your clothes. Although there is a lint filter that you clean out each time you do a load of laundry, not all of the lint gets caught in the filter. The lint that slips through or past the filter will get into the dryer casing, the dryer vent piping or even your walls. That lint will dry out and build up until it stops the air flow and can catch fire.
I found this great video from www.askmediy.com to show you how to clean out your dryer to prevent a fire hazard.