Bottle is a WSGI-compliant single source file web framework with no external dependencies except for the standard library included with Python.
The official Bottle tutorial provides a thorough view of basic concepts and features for the framework.
Digital Ocean provides an extensive introductory post on Bottle.
This tutorial provides a walkthrough for getting started with Bottle.
Here's a short code snippet for creating a RESTful API with Bottle and MongoDB.
This tutorial is another Bottle walkthrough for creating a RESTful web API.