DIN is the scale that measures how much force it takes for your binding to release your boot in a fall. A higher DIN means the binding holds tighter before letting go. Your ideal DIN is calculated using your weight, skiing ability, and boot sole length—most ski shops use a standard DIN chart to find this number.
When shopping for bindings, choose a pair where your recommended DIN falls in the middle third of the binding's range. This gives you room to adjust as you improve. Most beginners land around DIN 3-5, intermediates around 5-7, advanced skiers around 7-10, and experts and racers typically need 10 and above.
Avoid the common mistake of buying race bindings (DIN 12-18) just because they seem more serious—if your setting sits at the very bottom of the range, the binding may not release properly when it should. And never crank your DIN higher than recommended to stop occasional pre-release; that's a real safety risk.