Out of the box, very little. They're like an old school charcoal grill with vents you open/close to adjust the temperature.
There's several aftermarket temperature controls for them I don't remember the brand of mine, but it has a fan you mount to the smoker, a temperature probe inside, and a control unit. You plug it all in, light the charcoal, set the temperature, and let it run. It's great for things that need to smoke for 12 or 14 hours. I feel comfortable letting it run unattended overnight so I can get decent sleep and still have meat ready for lunch.