what is synchronous and asynchronous in javascript

In JavaScript, synchronous code runs in sequence, meaning that each operation must wait for the previous one to complete before executing. Asynchronous code, on the other hand, runs in parallel, allowing operations to occur while others are still being processed. Asynchronous code execution is often preferable in situations where execution can be blocked indefinitely, such as network requests, long-running calculations, and file system operations. Using asynchronous code in the browser ensures that the page remains responsive and the user experience is mostly unaffected. Some common examples of asynchronous operations in JavaScript include browser API/Web API events or functions like setTimeout, or event handlers like click, mouse over, and scroll. Promises are another unique JavaScript object that allows for asynchronous operations.