Gnats are a type of insect that form clouds when they swarm together. They are small, flying insects that are related to mosquitoes and midges. Gnats are often found in large numbers near water sources, such as ponds, streams, and lakes. They are also attracted to light and can be seen swarming around street lights at night. Gnats are considered to be a nuisance, but they do not pose any real threat to humans.