How to get rid of a double chin?

I've lately been noticing a double chin developing on my jawline and its starting to annoy me.

Why do people get this and is there a way to reverse it?

If your double-chin is due to forward head posture and weak neck musculature, it's easy to fix with exercise; they actually call it the double-chin exercise. If due to fat accumulation, it's way tougher to reverse in stubborn areas like chin and abdomen. My advice is to look into lowering overall body fat with diet and exercise such as HIIT. Set your goal, start slow and chip away a little every day.

Look up the Lion exercise (yoga). And yes, if needed, lose weight.

it happened to me too ...i saw it ferst time after doing mm scalp massage .... i dont know may be relaxing scalp muscle cause sag under chin...or it just there b4 massage and i just notice that because i look too much at the merror