PHP is a open source server side scripting and interpreted programming language allows web developers to create dynamic content that integrated with a number of popular databases, including MySQL, PostgreSQL, Oracle, Sybase, Informix, and Microsoft SQL Server. It is faster than other scripting language widely used in web development and it can develop dynamic websites easily.
ASP.NET is a web development framework for developing dynamic web applications. It is a part of Microsoft .Net platform allows you to use a full featured programming language which produce interactive, data-driven web applications over the internet as well as mobile devices. It helps in storing the information regarding the state of applications which are page state and session state.