I assume that people laugh because they hear or see something humorous. Or sometimes they laugh in order not to cry and feel bad and embarrassed.
Judaism regards laughter as having the potential to be very beneficial. When used properly laughter and certain jokes can uplift a person and bring them to a place that makes connecting with God easier and better.
However, we are taught that laughter and humor can be misused and they can be very destructive. That is when the humor and the laughter are directed towards a person in a way that either hurts the feelings of the person, or that crosses over the boundaries of what is acceptable speech and what is not.
Here is an example of the potential importance of “positive humor” and its reward. Rabbi Broka was often in the market where Elijah the Prophet spoke to him. Each day, he asked Elijah, "Is there anyone here who merits the eternal world?" to which Elijah 's reply repeatedly was, "No." One day, Elijah said, "Those two." Rabbi Broka excitedly asked them, "What special thing do you do?" They answered, "We're comedians. We cheer up depressed people." (Talmud, Ta’anit 22a).
