I have a friend who always talks about coding on his whatsapp status, he even posted a screenshot of a mobile app he allegedly was working on. So, i asked him what language he uses to Develop Mobile apps (not web apps) and he said, html, css and php. I am a beginner in programming, i know java, python, dart and Javascript can be used to develop mobile apps,can we also use html, css and php to develop mobile apps?