To laugh means to make sounds or movements so as to express amusement or fun. Laughing is nothing but an act of laughing. One laughs when one gets amused. After listening to a funny joke or some sort of comedy that if really hilarious, you laugh your heart out. Laughter is the best medicine. People who laugh a lot and stay happy are the ones who keep healthy and fit. Laughter is a means of giving vent to all the energies and positive feelings within you. You erupt with laughter watching laugh riots also.
In the words of Judith Viorst, “Close friends contribute to our personal growth. They also contribute to our personal pleasure, making the music sound sweeter, the wine taste richer, the laughter ring louder because they are there.” Comedy is defiance. It's a snort of contempt in the face of fear and anxiety. And it's the laughter that allows hope to creep back on the inhale. So laugh a lot and stay fit and healthy.