Here we use builder.mutation() to define a mutation in our API. What is a mutation? Well it’s basically a POST request or anything that would modify something on the server. You’ll notice builder.mutation() and builder.query() look very similar except here we are passing the URL in an options object and that’s only because we want to pass method and body as well. The query here could potentially also be a string just like in builder.query.
The most interesting thing about mutations is optimistic updates which we’ll cover in a later lesson about onQueryStarted.
More information about the options you can pass into builder.mutation can be found here:
https://redux-toolkit.js.org/rtk-query/usage/mutations