A common tagline for GraphQL is that it's a query language for your API or a way of asking questions of our data. This is true, but GraphQL also provides us with a type system for our APIs. In this talk, we'll take a closer look at how this type system in combination with Apollo Server allows us to mock data sources on the client and server. We'll learn to create custom mocks on the server, and we'll use the client directive to enable mocking for client-side fields. These techniques will help you move faster as you prototype and build your own solutions with GraphQL.