What is the purpose of enqueueAction in helper.js in lightning in Salesforce?

$A.enqueueAction(action) adds the server-side controller action to the queue of actions to be executed. All actions that are enqueued will run at the end of the event loop. Rather than sending a separate request for each individual action, the framework processes the event chain and batches the actions in the queue into one request. The actions are asynchronous and have callbacks.

$A.enqueueAction(action) sends the request to the server. It adds the call to the queue of asynchronous server calls.