Usage of Trigger.IsExecuting in Salesforce

Trigger.isExecuting is to determine that your current context for the Apex code is a trigger, not a Visualforce page, a Web service, or an executeanonymous() API call.
Here is an example of Apex Class, this class can identify current context for the Apex code is a trigger using Trigger.isExecuting.

Apex Class:

public class AccountHandler
    public Boolean handleAccount(List<Account> accList){
        System.debug('Trigger is executing : ' + Trigger.isExecuting);
			//Do what ever you want to do as part of the trigger invocation
            //Do what ever you want to do if the call originated from different context, such as from controller.
        return Trigger.isExecuting;

Apex Trigger:

trigger AccountTrigger on Account (before insert, before update){
    AccountHandler handler = new AccountHandler();