In the rapidly growing Internet of Things (IoT), applications from personal electronics to industrial machines and sensors are getting wirelessly connected to the Internet. Covering a wide variety of use cases, in various environments and serving diverse requirements, no single wireless standard can adequately prevail. With numerous standards deployed in the market, choosing the right wireless connectivity technology for an IoT application can be quite challenging. This paper reviews the predominant wireless connectivity technologies in the market, discusses their key technical concepts and engineering tradeoffs and provides guidelines for selection of the right wireless technology for different applications.