ASP, or Active Server Pages, is a server-side scripting technology developed by Microsoft. It allows developers to create dynamic web pages by embedding scripts within HTML. When a user requests a page, the server processes the scripts and generates HTML content that is sent to the user's browser. ASP uses languages like VBScript or JavaScript for scripting, enabling functionalities such as database interaction and user input processing. It is commonly used in conjunction with IIS (Internet Information Services) to build interactive web applications. ASP has evolved into ASP.NET, which offers more features and improved performance for modern web development.