An artificial satellite is an object intentionally placed into orbit around a celestial body, such as the Earth. They are human-made devices that are sent into space to orbit Earth or other Solar System objects, where gravity keeps them in orbit. There are currently over 3,000 active satellites orbiting the Earth. Artificial satellites can be built to perform various tasks, including communication relay, weather forecasting, navigation, broadcasting, scientific research, and military applications. They can also be used to take aerial photographs of Earth that help meteorologists predict the weather, or take pictures of astronomical bodies and distant galaxies, which helps scientists to better understand the cosmic system.

Artificial satellites vary in size, altitude, and design depending on their purpose. Some cube satellites are as small as 10 cm, while some communication satellites are about 7 m long and have solar panels that extend another 50 m. The largest artificial satellite is the International Space Station (ISS), which is as big as a large five-bedroom house, but including solar panels, it is as large as a rugby field.

Every usable artificial satellite has four main parts to it: a power system, a way to control its attitude, an antenna to transmit and receive information, and a payload to collect information (such as a camera or particle detector). Most satellites have solar panels to generate electricity, and batteries store some of this energy for times that the satellite is in the shadow of the Earth. Satellites are exposed to extremely high temperatures due to exposure to the Sun, so there needs to be a way to reflect and reradiate heat. Electrical components of the satellite can also produce a lot of heat, so a heat control system is necessary. Satellites need computers to control how they operate and also to monitor things like altitude, orientation, and temperature. All satellites need to be able to send and receive data to ground stations on Earth or to other satellites, so curved satellite dishes are used as antennae. A rocket engine on the satellite may be used to help place the satellite into the correct orbit.