Zoom-in
AI is making it easier than ever to skip the root of problems. This series goes the other way — each post picks one fundamental concept and zooms in, layer by layer, until it's truly understood.
There are moments when you hit a bug you can't explain, or need to design something from scratch — and realize you've been guessing more than knowing.
Zoom-in starts from that feeling. Each post picks one fundamental concept and asks the simplest question: what problem does this exist to solve? Then zooms in, layer by layer, until the answer is clear.
Posts in this series
Zoom-in: HTTP
Every web app starts from a simple model: client asks, server answers. HTTP is the language of that conversation — but five layers of infrastructure make it work.
Zoom-in: Database Index
Adding an index is the first thing everyone tries. Fewer people ask why it works — or when it becomes a liability.
Zoom-in: JWT
Log in, call an API, server lets you through. Inside that token is a digital signature — not encryption, and that distinction matters.
Zoom-in: Cache
Add Redis when it's slow. But where cache sits, how long it holds data, and when it clears — each wrong answer creates a different class of bug.
Zoom-in: Docker Container
docker run, app starts instantly — on any machine. Inside is the Linux kernel creating isolation without a virtual machine.
Zoom-in: Asymmetric Encryption
HTTPS is secure because it's encrypted. But who encrypted it, who decrypts it, and why no one can impersonate the server — that's the real question.
Zoom-in: DNS
Type 'google.com', press Enter. Your machine doesn't understand domain names — it only understands IP addresses. Between those two is a four-layer distributed lookup system.
Zoom-in: TCP
Every HTTP request runs on TCP — but before the first byte of real data crosses the wire, three packets are exchanged carrying no data at all. TCP solves the problem the Internet doesn't.
Zoom-in: OAuth 2.0
'Sign in with Google' hides a delegation mechanism where your password never leaves Google. OAuth 2.0 solves the authorization problem without sacrificing security.
Zoom-in: Load Balancer
One domain, millions of requests per day. A load balancer doesn't just split traffic — it decides routing, health checking, and session management for the entire system.
Zoom-in: Git Commit
git commit -m 'fix bug' — one command. Under the hood is an immutable, content-addressed data structure that explains why rebase, cherry-pick, and merge work the way they do.