The transport layer offers two fundamentally different approaches to delivering data. TCP, the Transmission Control Protocol, establishes a connection through a three-way handshake, guarantees that every packet arrives in order, and retransmits anything that gets lost along the way. UDP, the User Datagram Protocol, skips the connection setup entirely and fires packets without waiting for acknowledgments. TCP is ideal when accuracy matters, such as loading a webpage or downloading a file. UDP excels when speed matters more than perfection, powering voice calls, video streams, and online gaming.