A system and method for creating, rendering and controlling a user interface is provided. A server generates a mark-up language document containing custom tags and conventional tags. The custom tags are associated with machine-executable instructions operating on a client device. When the client device receives the markup language document containing custom tags, the client device processes the custom tags and inserts the machine-executable code into the document at the location of the custom tags. A browser operating on the client device then executes the code and renders the document on a display device.