The /store/ directory is used to contain the Vuex store files. You don't need to install Vuex in Nuxt because it already comes with Nuxt. It is disabled by default and you just have to add an index.js file to this directory to enable it. For example, if you want to have a property called auth that can be accessed from anywhere throughout your app.
You will have that property stored in the state variable in the index.js file, as follows:
// store/index.js:
export const state = () => ({
auth: null
})
We will look at this directory in more detail in Chapter 10, Adding a Vuex Store.