This tutorial will present an introduction to RyuJIT (rē-yü-jit), an industry leading, high performance Just-in-Time compiler that supports the Microsoft .NET ecosystem. RyuJIT is also used to deliver world class performance on in house 1st party services like Office 365, Bing, and Exchange through innovative design and focus on business results. RyuJIT is shipping in the .NET 4.6 product and is now open source as part of CoreCLR. An overview of the architecture of RyuJIT will be presented, including the internal representation (IR) and compilation phases with a focus on key design and implementation details that enable RyuJIT’s throughput/performance trade off. Participants will then be guided through the process of adding a simple feature to RyuJIT.