Message boxes are dialog windows predefined by the system and used as a simple interface for applications, without the necessity of creating dialog-template resources or dialog procedures. Message boxes are best for short notification messages that require a simple acknowledgment or choice by the user. Applications do not specify a dialog procedure for message boxes, so they cannot readily change the action of a message box. However, there is no need to do so, since there are many predefined message-box styles. There are two types of message boxes available to applications: standard and enhanced.