Explainer ·
The Cookies That Arrive Before the Page Does
A cookie needs no script and no banner. It can ride on the first response a site ever sends you, with an expiry date decades away that the browser quietly shortens.
Articles
14 articles, newest first.
Explainer ·
The Protocol You Only Get on the Second Visit
A browser cannot use HTTP/3 until something tells it the site supports it. Most sites say so in a response header, which arrives after the first connection is already made.
Explainer ·
The Response That Arrives Before the Response
A server can tell the browser what to fetch before it has built the page. That head start lasts exactly as long as the server is slow, and on fast sites it is close to zero.
Explainer ·
The Update That Weighs 98 Bytes
Every deploy makes your visitors re-download a bundle they already have 99% of. A standard published in September 2025 fixes that, and almost nobody has switched it on.
Explainer ·
The Snapshot Waiting Behind the Back Button
Two things used to guarantee the back button reloads a page from scratch. Chrome rewired one in 2025 and is deleting the other in 2026, mid-rollout right now.
Explainer ·
The Header That Carries Your Dark Mode
Your light or dark mode setting can leave the machine as an HTTP request header. The same channel carries your motion and contrast preferences too.
Explainer ·
What Replaced the User-Agent String
The User-Agent string was trimmed to leak less. The detail it carried did not disappear - it moved to a channel the server switches on, and one engine answers.
Explainer ·
The Request That Describes Your Device
Before your JavaScript runs, the browser can already have told the server how much RAM your device has and how fast your connection is, rounded off on purpose.
Explainer ·
The Page You Never Opened Has Already Loaded
Two hundred milliseconds of hover can be enough for the destination to load in full, run all of its JavaScript, and count you as a visitor.
Explainer ·
Not All Bytes Cost the Same
A kilobyte is treated as a fixed unit of harm. It is not: a kilobyte of JavaScript and a kilobyte of image do very different amounts of damage.
Explainer ·
The Codec Your Browser Picked, and Why It Was Not Your Choice
The same page can hand two people different encodes of one video. A negotiation before playback picks which, and the browser's answers are deliberately vague.
Explainer ·
What an Embedded Third-Party Script Actually Gets
A script tag and an iframe look like the same act of embedding. They are opposites: one hands over the page, the other holds the guest at arm's length.
Explainer ·
What Actually Happens to a Video Before You See It
A video is not a file you are sent. It is a few hundred short segments, published at several qualities, and a running guess about which one to fetch next.
Explainer ·
What a Page Knows About You Before You Click Anything
Loading a page is not a neutral act. A set of identifying details arrives with the request itself, before any script runs and before you touch the screen.