What is IEnumerators ?

IEnumerators are used to allow a program to yield things like the WaitForSeconds function, which tells the script to wait without hogging the CPU.

StartCoRoutine essentially runs a function in another thread when used with yield. The execution of a coroutine can be paused at any point using the yield statement. The yield returns a value specifies when the coroutine is resumed.

Example : In this example CPU will wait for 5 seconds and after that "This is the use of IEnumerator..." will be printed.

 public void function()
    {
        StartCoroutine (timing());               
    }
    IEnumerator timing()
    {
        yield return new WaitForSeconds (5.0f);
        Debug.Log("This is the use of IEnumerator...");
    }