Recently tremendous growth is observed with the advent of wireless technologies, which demand enormous spectrum bandwidth to provide high data rate multimedia applications to the users including video conferencing, telephony, and instant web browsing. Thus, the conventional radio frequency (RF) spectrum has become one of the scarcest resources; hence, the research arena has been forced to look beyond radio frequency communications and investigate other forms of wireless communication systems. The free space optical communication is one potential contender that is being implemented to fulfill the demand of high bandwidth wireless communication system. This chapter discusses the state-of-the-art aspects of FSO communication systems in detail along with the various factors that should be considered while designing and analyzing FSO communication ecosystems. Further, it also explores thoroughly converses about the means by which mixed RF/FSO cooperative relaying strategy could be implemented.