Have you heard of TDD? Are you interested or familiar with this practice but have never been able to understand it? In this session I'd like to present the benefits of Test-Driven Development (TDD), explaing how it works and what the benefits are of using it. We will see in a more detailed approach this way of developing software, where our software is always built guided by tests. We will go over some history about TDD, which is the main process we must follow when we work with this mechanic and the rules that surround it. We will also list the main advantages and disadvantages that most developers who practice TDD find and whether the arguments in favour add up to more than those that subtract. Finally, we will review some good habits and practices when applying TDD and see how to do it step by step with a Java code example. At the end of the session, I hope attendees will have a wider understanding of what TDD is, what advantages it brings, why it is interesting to master it and also that you will take with you some tricks and good practices to be able to apply them in your day-to-day life when writing code.