text: what is the difference between .asp and .aspx?   asp is microsoft's first-generation web scripting language.  it's not compiled code; like php, it is a series of scripted instructions to the server. the server picks up the page, reads the scripts, does what it's instructed to do, then sends the resulting html to the client.  asp works on the request-response model: i ask the web server for something (request) and it sends back whatever i asked for (response).  asp.net is compiled code. it is object-oriented, which means that it uses classes and other data structures to perform requested actions, rather than scripted instructions.   asp.net uses the event model. in other words, if you click on this or type in that or make another thing, then something else happens.  asp.net is more like desktop application programming than asp.  finally, asp is a legacy product, meaning the day is coming when microsoft won't support it any more.