This document provides an overview of Internet of Things (IoT) concepts including M2M architecture, devices, networks, standards, and market characteristics. It describes the key components of M2M architecture defined by ETSI including M2M devices, area networks, gateways, network/application domains, and capabilities. Trends in M2M standards from 3GPP, 3GPP2, ETSI, and others are discussed. Differences between M2M and IoT are outlined. Low-power wireless technologies for IoT like LoRaWAN, Sigfox, NB-IoT, LTE-M and IEEE 802.11ah are introduced along with their applications and limitations.