So far in our example app, we have only been fetching data from our GraphQL API endpoint. In this lesson, we’ll learn how to modify data on our server using GraphQL.

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In a REST API, we typically use GET requests to fetch something, and POST / PUT / PATCH / UPDATE requests to change data on the server.

In GraphQL, however, the distinction is a bit simpler:

• We use query when we need to fetch data
• We use mutation when we need to modify anything

Let’s explore how to edit a book’s information, and look at how this affects the Apollo cache and how the changes are reflected in our Vue app.

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Getting familiar with the updateBook mutation