Web caching is one of the most powerful techniques you can use to improve the performance of your websites. But like with many other optimization methods, it's not always clear where to start. When should you cache your resources? For how long? And how do you invalidate them? It can be an intimidating subject; but fear not, understanding its fundamentals is surprisingly simple. In this talk, I will walk you through the basics of HTTP Caching: how it works, how to manage it, and how to implement simple but effective strategies that will make your sites faster, leaner, and more responsive.