In this chapter, we describe the properties of wireless datalink protocols, focusing on WiFi and cellular as examples of high performance protocols in the unlicensed and licensed spectrum respectively. Before we discuss WiFi and cellular, we provide some background on datalink protocols in general. More detailed information on wireless protocols can be found in several textbooks on wireless communication and networking (Molisch 2022; Beard and Stallings 2016), in addition to standards documents and research papers.