What is Pinia and why has it replaced Vuex as the recommended state management library?

Pinia is Vue's official state management library, recommended over Vuex for new Vue 3 projects. Advantages over Vuex:

• No mutations — you update state directly in actions, simplifying the API.
• Fully typed, with excellent TypeScript inference out of the box.
• Lightweight and modular — stores are independent, tree-shakeable, and don't need nested modules/namespacing.
• Works naturally with the Composition API and devtools, and supports Options-API-style stores too.

import { defineStore } from 'pinia'

export const useCounterStore = defineStore('counter', {
  state: () => ({ count: 0 }),
  actions: {
    increment() { this.count++ }
  }
})