Transport layer protocols serve as the critical link between theory and practical application. Understanding protocol design is only half the story; observing how it performs under real-world stress reveals its true value. This chapter focuses on the practical implementation of transport layer protocols, analyzing differentiated performance requirements across scenarios such as cloud gaming (low latency), microservices (high connection efficiency), data centers, and high-performance computing. This chapter delves into optimization strategies tailored for different scenarios and introduces the MIN-QUIC-based MIN-HTTP/3 optimization within web protocols. Its core content features case studies from major tech companies like Meta, ByteDance, and others, demonstrating how they deploy QUIC at scale. Finally, a hands-on experiment enabling HTTP/3 in browsers helps students grasp how to select and optimize transport protocols based on application contexts, enhancing their engineering practice skills.