Spectral congestion is caused by too many RF communications users concurrently accessing the electromagnetic spectrum. This congestion may degrade communications performance and decrease or even restrict access to spectral resources. Spectrum sharing between radar and communications applications was proposed as a way to alleviate the issues caused by spectral congestion. This has led to a greater emphasis being placed by researchers into investigating methods of radar-communications cooperation and co-design. Government agencies such as The Defense Advanced Research Projects Agency (DARPA) and others have begun funding research that investigates methods of coexistence for military radar systems, such that their performance will not be affected when sharing spectrum with communications systems. These agencies are also interested in fundamental research investigating the limits of cooperation between military radar and communications systems that in the long run will lead to better co-design methods that improve performance. However, the problems caused by spectrum sharing do not affect just military systems. There are a wide variety of remote sensing and communications applications that will be adversely affected by sharing spectrum with communications systems such as automotive radars, medical devices, 5G etc. Furthermore, applications like autonomous automobiles and smart home networks can stand to benefit substantially by cooperative remote sensing and communications. Consequently, researchers have started investigating fundamental approaches to joint remote sensing and communications.