A cloud is a visible mass of water droplets or ice crystals suspended in the atmosphere. Clouds form when water vapor in the sky condenses into liquid form around things like dust, ice, or sea salt, known as condensation nuclei. The temperature, wind, and other conditions where a cloud forms determine what type of cloud it will be. There are many types of clouds, including cumulus, stratus, and cirrus clouds. Clouds are an important part of Earths weather and climate, and studying them helps scientists better understand precipitation, heat reflection, and other weather phenomena.

In addition to the atmospheric definition, the term "cloud" is also used in the context of computing. Cloud computing refers to the on-demand availability of computer system resources, such as data storage and computing power, without direct active management by the user. The cloud is a distributed collection of servers that host software and infrastructure, and it is accessed over the Internet. Cloud computing has become a solution for use cases including business analytics and geospatial analysis.