AWS IoT enables secure, bi-directional communication between Internet-connected things (such as sensors, actuators, embedded devices, or smart appliances) and the AWS Cloud over MQTT and HTTP.

Developer Guide
Walks through how to set up AWS IoT and integrate it with other services.

AWS IoT sections of the AWS CLI Reference
Describes the AWS CLI commands that you can use to administer and manipulate AWS IoT.
IoT | IoT-Data

API Reference
Describes all the API operations for AWS IoT in detail. Also provides sample requests, responses, and errors for the supported web services protocols.

Thing Shadow REST API
Describes all of the REST API operations for working with Thing Shadows.