This chapter studies the problem of UAV deployment for wireless communication purposes. In particular, we focus on the deployment of UAV base stations whose locations will strongly impact the performance that they can deliver. To this end, we start by providing a broad overview on the analytical tools that can be used to develop optimized deployment strategies for wireless networks with UAVs. Then, we investigate how UAV base stations can be deployed for optimizing the wireless coverage for a ground network of wireless devices that seek to communicate with UAV BSs in the downlink. We shed important light on how to deploy the UAV base stations, by determining their number and locations, in a way to maximize network performance, under various constraints, such as power. We then investigate the problem of optimally deploying UAV base stations for collecting data, in the uplink, from ground Internet of Things devices in an energy-efficient manner. We conclude our discussions by studying the deployment of UAV base stations that can leverage machine learning techniques to cache popular content and to track the mobility of ground users.