What type of satellites need hundreds to thousands to fully cover the Earth?

Low Earth Orbit (LEO) satellites are positioned much closer to Earth, typically at altitudes ranging from about 180 to 2,000 kilometers. Because of their proximity, they have a limited coverage area on the Earth's surface at any given time. To achieve global coverage, a network of hundreds to thousands of these satellites is required to ensure that different parts of the planet are effectively monitored or served, as they move quickly across the sky and have a relatively small footprint.

In contrast, geosynchronous satellites are stationed much higher, approximately 35,786 kilometers above the equator. At this altitude, they remain in a fixed position relative to the Earth's surface, allowing for continuous coverage of specific regions without the need for a large number of satellites.

Radio Frequency Identification (RFID) and Infrared (IR) are not types of satellites; instead, they refer to technologies used in tracking and communication. RFID is predominantly used for tagging and tracking items, while IR often pertains to imaging and sensing technologies used in various applications, including satellites. These technologies do not represent satellite types that cover the Earth.