This paper explains the process of creating mobile applications for the Android operating system. The principles of object-oriented programming, and programming languages Java and XML are explained in the introductory part of the paper. An overview of the development tools used: Java Development Kit and Android Studio, which are all available for free download on the official website of Java and Android. The starting point in the development of any application is the idea what the application will do after which programmer creates a vision of how an application should look like on screen. That part of the development takes place in the XML language in which programmers define objects he wants to display and their position and appearance. A key part of the development of successful applications, particularly successful mobile applications, is to develop an efficient and intuitive user interface. A programmer decides how and in what way will he allow the interaction while using a programming language, in this case Java. This paper describes the entire process of development in the case of specific applications.