Component Lifecycle: Mounting

Because it's the fastest lifecycle method
Because it only executes on the server
Because the component is already rendered in the DOM
componentDidMount is a good place to make API calls because the component is already rendered in the DOM at this point. This means you can update the state with the API response without worrying about trying to update a component that hasn't mounted yet, and the user can see the initial render while waiting for data.
Because API calls are not allowed in other lifecycle methods