If you're learning React, you've probably heard these terms everywhere:

React.memo

useMemo

useCallback

At first, they look confusing.

But all three solve one major problem :

⚡ Unnecessary Re-renders & Performance Issues

This guide explains:

what each one does

why they exist

how they are connected

when to use them

interview explanations

🤔 Why Do These Exist?

In React, components re-render very frequently.

A component re-renders when:

state changes

props change

parent component re-renders

Most of the time this is fine.

But in large applications:

expensive calculations

recreated functions

unnecessary child renders

can slow down the application.

That’s why React provides:

React.memo

useMemo

useCallback

for optimization.

🧠 First Understand One Important Thing

In React:

function App () { console .…