The difference between Asynchronous and Synchronous code is that Asynchronous code does not block the execution of the program while Synchronous code does.
Asynchronous code
Asynchronous code is executed in the background and it does not block the execution of the program. It is usually used to perform tasks that take a long time to complete, such as network requests.
console.log('Before');
setTimeout(() => {
console.log('Hello');
}, 1000);
console.log('After');Synchronous code
Synchronous code is executed in sequence and it blocks the execution of the program until it is completed. If a task takes a long time to complete, everything else waits.
console.log('Before');
for (let i = 0; i < 1000000000; i++) {}
console.log('After');