Above is the version with Transmit Power amplifier and Receive Preamplifier. Our low-cost antenna is on the unit shown on the right. The same 8 pins connect to Arduino and the same software is used.
Here's a link to a Home-Brew antenna design:
These transceivers use the 2.4 GHz unlicensed band like many WiFi routers, some cordless phones etc.
Transceivers like these both send and receive data in 'packets' of several bytes at a time. There is built-in error correction and resending, and it is possible to have one unit communicate with up to 6 other similar units at the same time.
These amazing low-cost units have a lot of internal complexity but some talented people have written Arduino libraries that make them easy to us. We have other pages that show examples and point to the free software libraries you may need. They all use the same pinout as shown in the following diagram, which is a TOP VIEW (Correction!):