Each of those languages are general purpose languages meaning you can use them to make anything. Ярослав Вернигора (Yaroslav Vernigora) gave the main reason they exist. But, that does not limit them. I have built a PC and an Android app with Kotlin. I could build an iOS app with it or use it as the server backend of a web app. I can also use it in an embedded processor system like a microwave or TV.