What is the difference between synchronous and asynchronous API calls?

Synchronous API calls block the execution of the program until a response is received from the server. This means that subsequent code does not execute until the request is completed.

Asynchronous API calls allow the program to continue executing without waiting for a response. The response is processed later, for example, via callback, promise, or async/await.

Example:

• Synchronous call: the program waits for data to load and only then continues.
• Asynchronous call: the program sends a request and immediately continues working, and when the data arrives — processes it separately.

Asynchrony improves the responsiveness of applications and allows efficient handling of slow operations, such as network requests.