One of the frequent question that comes during the .NET interview is “What is the difference between string and String?” . This one is a very simple question but can make you confused during the interview. So, let’s try to recall and check what exactly they are. To answer this question in a short, The two are indeed synonymous. String stands for System.String and string is an alias for String. There is no actually any different, both of them compiled into same code (IL Code – System.String) and they are same during execution time.