This introduction will give an introduction and live demonstration of the OGC SensorThings API. The OGC SensorThings API provides an open and unified way to interconnect the Internet of Things (IoT) devices, data, and applications over the Web. The OGC SensorThings API is a new OGC standard candidate. Unlike many existing OGC standards, SensorThings API is very simple and efficient. At the same time, it is also comprehensive and designed to handle complex use cases. It builds on a rich set of proven-working and widely-adopted open standards, such as the OGC Sensor Web Enablement (SWE) standards, including the ISO/OGC Observation and Measurement (O&M) and Sensor Observation Services (SOS). The main difference between the SensorThings API and the OGC SOS is that the SensorThings API is designed specifically for the resource-constrained IoT devices and the Web developer community. As a result, the SensorThings API follows the REST principles, the use of an efficient JSON encoding, and the use of the flexible OASIS OData protocol and URL conventions. In addition to introduce the specification, this talk will also demonstrate an end-to-end IoT application based on the SensorUp IoT platform, an open source implementation of the SensorThings API, including a server, javascript library, web dashboard and a Arduino library.