Can you explain the differences between synchronous and asynchronous programming in the context of backend development? Provide examples of when you would use each.

Synchronous programming waits for a process to complete before moving to the next line of code, leading to a blocking operation. Async programming, on the other hand, allows other processes to run without waiting, making it non-blocking. Use synchronous for tasks where order is crucial (e.g., transactions) and async for I/O-bound tasks to improve responsiveness (e.g., file uploads).