Async Function

Understanding Async Code (Without the Confusion)

Many beginners hear async and think it means doing many things at the same time. That sounds reasonable — but it’s not what async really means.

Let’s fix that.

The Core Idea

Async does NOT mean parallel.

Async means deferred.

Think of async code as a to-do list. The program finishes what it is doing now, postpones slow tasks, and comes back to them when they are ready.

One Brain, One Task

Both JavaScript and Python behave like a single person with one brain:

• They run code top to bottom
• They do one thing at a time
• They don’t multitask by default

Async allows them to avoid waiting and freezing while slow tasks complete.

Real-Life Analogy

Imagine cooking:

1. You put food in the oven
2. You don’t stare at the oven
3. You clean the kitchen
4. The oven beeps
5. You go back to the food

The oven is async. You deferred the task instead of blocking yourself.

JavaScript Example (Async Is Deferred)

console.log("Start");

setTimeout(() => {
  console.log("Async Task Done");
}, 1000);

console.log("End");

      

Output

Start
End
Async Task Done

      

JavaScript does not pause execution. It defers the task and continues running until it is free to return to it.

JavaScript with async / await

async function fetchData() {
  console.log("Fetching data...");

  await new Promise(resolve => setTimeout(resolve, 1000));

  console.log("Data received");
}

fetchData();
console.log("Other work");

      

Output

Fetching data...
Other work
Data received

      

The await keyword pauses execution only inside the async function. The rest of the program continues running.

Python Example (Same Concept)

import asyncio

async def task():
    print("Async task started")
    await asyncio.sleep(1)
    print("Async task finished")

async def main():
    asyncio.create_task(task())
    print("Doing other work")

asyncio.run(main())

      

Output

Doing other work
Async task started
Async task finished

      

Python defers execution using asyncio. The program resumes the task when it is ready instead of blocking.

Python vs JavaScript

Concept	JavaScript	Python
Async keyword	async	async
Pause execution	await	await
Non-blocking sleep	setTimeout / Promise	asyncio.sleep()
Meaning of async	Deferred work	Deferred work

What Async Is NOT

• Not multi-threading
• Not true parallel execution
• Not faster CPU processing

Async is about waiting efficiently, not working simultaneously.

Final Thought

Async code is work that is postponed and resumed later, not work that runs at the same time.