Difference between synchronous and asynchronous in apex

Hello Shubham,

An async call is queued up in Salesforce and run on a separate thread of execution. At this point it becomes decoupled from the calling action. That also means the calling action won't block and wait for a response from the asycn call. Using the future annotation identifies methods that are executed asynchronously. They must also be static methods. There are some considerations to know when using async methods.

you can learn more here: http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_classes_annotation_future.htm

Synchronous:

In a Synchronous call, the thread will wait until it completes its tasks before proceeding to next. In a Synchronous call, the code runs in single thread.

Example:

Trigger
Controller Extension
Custom Controller

Asynchronous:

In a Asynchronous call, the thread will not wait until it completes its tasks before proceeding to next. Instead it proceeds to next leaving it run in separate thread. In a Asynchronous call, the code runs in multiple threads which helps to do many tasks as background jobs.

Example:

Batch
@future Annotation

Thanks

Hi Everyone,
So basically in Salesforce, Apex can be executed in two ways: synchronously and asynchronously. Here's a simple breakdown:
Synchronous: This is like a two-way conversation. You ask a question, you get an answer right then. In synchronous processing, the code runs in a single thread, in the same sequence it's written, and the user waits for the request to complete before they can continue with their work. It's immediate, but it can also cause the user to wait if the process is long or complex.
Asynchronous: This one's more like sending a letter. You send it off and go about your day, knowing you'll get a response later. Asynchronous processing in Apex allows you to run processes in the background while users continue with their work. This can be particularly useful for complex, time-consuming processes that you don't want to make the user wait for. Apex provides @future methods, Queueable Apex, Batch Apex for this kind of processing.
Hope this helps!