Laptops accumulate dust during their lifetime just by being on. This is caused by the cooling fans that suck air into the laptop case. Dust can be a problem for laptops because it can build up on the cooling hardware and reduce its effectiveness. Periodically cleaning a laptop will keep it from overheating due to dust build-up. The most convenient way to remove the dust from cooling hardware, such as the fans, involves spraying compressed air into the laptop.
Take your laptop outside. This process will cause dust to spray out of your laptop, so it is best to do it where this won't make a huge mess. Also, some cans of compressed air have a horrible smelling additive that should not be used indoors.
Turn off the laptop.
Locate the side vents on the laptop. These are normally towards the back of the machine, on either side or the rear of the laptop. They look like little plastic grills, and one vent will be for exhausting warm air. This is the vent with the fan.
Place the nozzle of the compressed air can inside the fan vent located in the previous step. The nozzle doesn't have to go in far -- about a quarter inch is far enough.
Press the trigger on the can of compressed air to release a burst of air into the laptop. The force of the burst will disperse the dust from the fan.