Communication satellites are used to receive and redirect communication signals.

Explanation:
Communication satellites play a vital role in modern telecommunications systems, providing long-distance communication capabilities across the globe. These satellites are positioned in geostationary orbits, which means they remain fixed relative to a specific location on Earth, allowing for continuous coverage of a particular region.

Receiving Communication Signals:
One of the primary functions of communication satellites is to receive communication signals from ground-based transmitters. These transmitters can be various sources such as television stations, radio stations, telephone networks, and internet service providers. The satellite's receiver antenna picks up these signals and converts them into a form that can be processed and transmitted.

Redirecting Communication Signals:
Once the communication signals are received, communication satellites then redirect them back to Earth. They achieve this by amplifying and retransmitting the signals to specific ground-based receiving stations or other satellites in different locations. This redirection enables long-distance communication, allowing people to communicate across continents and even between remote areas where terrestrial communication infrastructure may be limited or unavailable.

Advantages of Communication Satellites:
- Global Coverage: Communication satellites provide global coverage, allowing communication signals to reach even the most remote areas of the world.
- Reliability: Satellites offer reliable communication services as they are not susceptible to physical obstructions or weather conditions like terrestrial communication infrastructure.
- Scalability: Satellite communication systems can handle large volumes of communication traffic, making them suitable for mass communication applications such as broadcasting and internet connectivity.
- Flexibility: Satellites can be repositioned or replaced to adapt to changing communication needs, making them highly flexible in providing communication services.

Conclusion:
In summary, communication satellites are crucial in facilitating long-distance communication by receiving and redirecting communication signals. They play a significant role in connecting people across the globe and providing reliable and scalable communication services.