Nowadays, anyone can use the internet applications very easily. The design of User interface (UI) has a great effect on facilitating the interaction of Internet user with web applications. In this paper, several issues of (UI) design for web applications are studied. The guidelines and architecture for the design of web applications as well as the nature of the web medium are discussed. Furthermore, the basic web application technologies are reviewed. In addition, the languages and frameworks used in building UI of web applications are described. We reach the concept that the future of web2 could bridge the gab between desktop and web applications UI. Moreover, the web as a platform and building a web operating systems could enhance the UI for web applications.