WiMAX/802.16 is a kind of network providing IP-based broadband wireless access to infrastructure networks such as the Internet. The two main envisioned applications are Web access and voice over IP. Highlights of WiMAX/802.16 are secure communications and broadband access in remote areas. This chapter covers the background, physical layer, medium access control layer, mobility support, mesh mode and multihop relay operation of WiMAX/802.16. The chapter ends with a presentation of thoughts for practitioners and a discussion of directions for future research