04 Try it yourself Interactive
The same page is asked for at t = 0 s, t = 20 s and t = 70 s. Each press moves one step: the two panels are the messages on the wire with the header that matters outlined in indigo, and the three boxes underneath are what the browser is holding, so you can watch the cookie jar and the cache entry fill up and the freshness run down. Every byte count is measured by counting the header lines you can see, so the totals always agree with the screen. Switch to Cache-Control: no-store to run the identical three requests with nothing allowed to be stored, and compare the two totals at the bottom. Change the body size and the freshness window and everything recomputes. Nothing plays on its own: Next, Back and Reset, or the arrow keys.