Most modern programming languages, in the hopes of enhanced maintainability and reusability of code, offer some constructs that help the developer keep the definition of behavior and its implementation separate. Swift takes the idea of interfaces a step further with protocols. With protocols and protocol extensions, Swift allows developers to enforce elaborate conformity rules without compromising the expressiveness of the language. In this article, Toptal Software Engineer Alexander Gaidukov explores Swift protocols and how protocol-oriented programming can improve the maintainability and reusability of your code.