Protocol Explorer is a free interactive learning tool that simulates network traffic to explain how internet protocols work. It presents animated packets moving between devices such as a laptop, router, internet service provider, and server, and decodes packet contents in an inspector. Lessons cover 39 protocols across the network stack, including HTTP, HTTPS, TCP, TLS, DNS, Ethernet, Wi-Fi, BGP, and WireGuard. The interface and lessons are available in eight languages. A typical lesson begins with a network diagram and a packet exchange. Users can play an animation, follow packets in a list or sequence diagram, and inspect individual packets to view decoded header fields alongside the corresponding raw hexadecimal bytes. Step by step tutorials explain exchanges such as the TCP handshake, DNS lookup, TLS negotiation, and HTTP request and response. Playback speed controls, step mode, keyboard shortcuts, and saved lesson progress support different learning paces. The tool is intended for people studying networking, preparing for certifications, or exploring what happens when a browser connects to a website. HTTP and HTTPS lessons are available at no cost. The site states that a one time payment unlocks the remaining protocol lessons, with no subscription or renewal. Progress is saved in the browser.