The Web as a Protocol: Requests, State and Caching
The web runs on a request and response protocol that remembers nothing between calls, so any sense of a session is built on top with cookies or tokens. Caching headers decide what may be reused and for how long, which is most of what makes the web feel fast.
What a learner can do afterwards
- Read a request and response pair and name the parts that carry meaning
- Explain how a stateless protocol supports a logged-in session
- Say what a caching header changes for a browser and for an intermediate cache
1 · Read
The web runs on requests and responses. Your browser sends a request with a method, a path, and headers. The server answers with a status, headers, and a body.
The protocol remembers nothing between calls. Each request stands alone, with no memory of the last one. That forgetfulness is called stateless.
Logging in sets a cookie in your browser. Your browser then sends that cookie with every later request. The server reads it and knows it is still you.
Caching headers say what may be reused and for how long. The browser keeps its own copy, and so do caches in between. That reuse is most of what makes the web feel fast.
Requests forget, cookies remind, and caching headers decide what gets reused.
2 · Watch
Take it off screen
Where it sits
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.