# Synchronous and Asynchronous Calls with the AJAX Toolkit

The AJAX Toolkit supports both synchronous and asynchronous calls.

Asynchronous calls allow the client side process to continue while waiting for a call back from the server. To issue an asynchronous call, you must include an additional parameter with the API call, referred to as a callback function. Once the result is ready, the server invokes the callback method with the result.

- **[API Call Syntax in the AJAX Toolkit](/docs/platform/ajax/guide/sforce-api-ajax-call-syntax.md)**

  SOAP API calls use slightly different syntax in AJAX Toolkit, depending on whether the call is synchronous or asynchronous.