Clouds are made up of many millions of miniscule water droplets which are formed when moist warm air rises up into the sky and is then cooled down. If the cloud is very cold it means that it is made up of ice crystals. It takes somewhere between a few minutes and 1 hour for a cloud to be created.
There are now a number of basic cloud types with names based on combinations of the above words, as well as the word 'alto' which is now being used to describe medium level cloud. These main cloud types can be placed into three different sections depending on their height from the ground.