
		 = and != are the symbols for Equals and Not-Equals.  

One value equals another if their values are the same, whether those values are numeric (5 = 5) or strings ('aaa' = 'bbb').  

Two values are not equal if their values are different even in the smallest degree (24.99999998 != 24.99999999).  

If you want to specify a list of employees whose last name is Brown, you would use = for the operator and 'Brown' for the comparison value.  If you used !=, you would get a list of employees whose last name is not 'Brown'.
	
