It is 2019. Most people have heard of Bitcoin, maybe Ethereum, too, and other altcoins. Having a current market cap of more than $309.71 billion it is definitely a technology, that we should be aware of, as well as know how we can implement any of the current decentralization solutions in our projects. In this session I want to talk about Blockchains and Ethereum as an introduction, to get a rough idea of how it works, followed by a showcase of a real use case demo, showing how to write our own Smart Contract using Solidity and the Ethereum Network, and finally talking about how we can interact with our Smart Contract from an Mobile Android Demo App, using either Kotlin or Java.