App is a term for application or program in historical computer terms. I'm sure people had been saying app for years since most everyone involved in computers love short word terminology and nicknames. Apple was probably the first to give the term a proper name for the mini applications used on smartphones. They went so far as to be the first to call them Apps and even officially named their store App Store. And they even tried copyrighting the term but got nowhere with it. So apps are what they are now and is usually in reference to tiny programs once called widgets and applets but now full blown PC programs are starting to be called apps as well.