A low earth orbit (LEO) satellite is an object, generally a piece of electronic equipment, that circles around the earth at lower altitudes than geosynchronous satellites.

LEO satellites are generally less costly to place as they require a great deal less rocket power to place. As compared to geosynchronous orbiting satellites at 36,000 km, LEO travel through a much denser atmosphere and thus experience far more aerodynamic drag.

Communications satellites in LEO often work as part of a large combination or constellation, of multiple satellites to give constant coverage. In order to increase coverage, sometimes constellations like this, consisting of several of the same or similar satellites, are launched together to create a ‘net’ around Earth. This lets them cover large areas of Earth simultaneously by working together.

A network of LEO satellite nodes can provide continuous coverage by communicating with Earth-bound transmission stations as the satellites circle the Earth. Their proximity to the planet's surface results in lower latency and the ability to support services that require faster throughput than traditional satellite internet.

LEO satellite is categorised into two types:

Little LEOs: Intended to work at communication frequencies below 1 GHz using no more than 5 MHz of bandwidth and supporting data rates up to 10 kbps. These systems are aimed at paging, tracking, and low-rate messaging. Orbcomm is an example of such a satellite system. It was the first (little) LEO in operation; its first two satellites were launched in April of 1995. It is designed for paging and burst communication and is optimized for handling small bursts of data from 6 to 250 bytes in length. It is used by businesses to track trailers, rail- cars, heavy equipment, and other remote and mobile assets. It can also be used to monitor remote utility meters and oil and gas storage tanks, wells, and pipelines. It can be used to stay in touch with remote workers anywhere in the world as well. It uses the frequencies 148.00 to 150.05 MHz to the satellites, and 137.00 to 138.00 MHz from the satellites. It has well over 30 satellites in low earth orbit. It supports subscriber data rates of 2.4 kbps to the satellite and 4.8 kbps down.

Big LEOs: Work at frequencies above 1 GHz and support data rates up to a few megabits per second. These systems tend to offer the same services as those of small LEOs, with the addition of voice and positioning services. Globalstar is one example of a big LEO system. Its satellites are fairly rudimentary. Unlike some of the little LEO systems, it has no onboard processing or communications between satellites. Most processing is done by the system's earth stations. It uses CDMA as in the CDMA cellular standard. It uses the S band (about 2 GHz) for the down- link to mobile users. Globalstar is tightly integrated with traditional voice carri- ers. All calls must be processed through earth stations. The satellite constellation consists of 48 operating satellites and 8 spares. They are in 1413-km-high orbits.