Callbacks & Callback Hell

Sync callbacks are faster
Async callbacks always use more memory
Sync callbacks execute immediately, async callbacks are deferred
The main difference between synchronous and asynchronous callbacks is their execution timing: 1) Synchronous callbacks execute immediately within the current execution context, 2) Asynchronous callbacks are deferred to a later time, usually the next event loop iteration, 3) Sync callbacks block execution until they complete, 4) Async callbacks allow other code to execute while waiting for completion, 5) This timing difference affects error handling, stack traces, and program flow.
Async callbacks can't handle errors