A concise but thorough introduction to GraphQL. GraphQL is very popular in API development because it allows you to exchange fewer data between client and server, than your average REST API application.
The author starts by showing how to set up the GraphQL endpoint first with Express, then specifying the schema for a basic Todo app, doing a few queries, connecting Mongo as a DB, and doing mutation queries (updates, deletes). Lastly, a React front-end is hooked up to complete the app.
I found this book useful because the author's style is practical and to the point, which makes the learning process pleasant for beginners.