# Introduction

Welcome to the Cosmos-SDK Core Documentation. 

Here you will learn how to use the Cosmos-SDK to build Basecoin, a 
complete proof-of-stake cryptocurrency system

We proceed through a series of increasingly advanced and complete implementations of 
the Basecoin application, with each implementation showcasing a new component of
the SDK:

- App1 - The Basics - Messages, Stores, Handlers, BaseApp
- App2 - Transactions - Amino and AnteHandler
- App3 - Modules - `x/auth` and `x/bank`
- App4 - Validator Set Changes - Change the Tendermint validator set
- App5 - Basecoin - Bringing it all together