Articles
The explanation you wish you'd found the first time you Googled it. No fluff, no 30-paragraph intro before the point.
NetworkingWhy localhost has two addresses
Type localhost and you usually hit 127.0.0.1. Sometimes you hit ::1 instead, your app works in one terminal and dies in another, and nobody tells you why. Here's the actual reason.
Jun 19, 2026 · 9 min read
System DesignHow Stripe actually works
Your card gets charged in under a second, across half a dozen systems, in a way that survives a server dying mid-payment. I traced one $20 charge from click to settlement.
Jun 14, 2026 · 14 min read
System DesignHow Discord serves millions of messages a second
One channel, a hundred thousand people typing at once. Discord stores it in a data model most tutorials tell you never to build. Here's why it holds up.
Jun 9, 2026 · 13 min read
GitHow GitHub stores your Git history
A commit isn't a diff. It's a snapshot, hashed and deduplicated, pointing at the one before it. Once that clicks, every confusing Git command turns simple.
Jun 3, 2026 · 11 min read
AI & AgentsHow Cursor reads your whole codebase
It doesn't send your repo to a model. It chops it up, embeds it, and retrieves the three files that matter right before it answers. The trick is in what it leaves out.
May 27, 2026 · 12 min read
AI & AgentsHow MCP actually works
Everyone's shipping MCP servers; far fewer can tell you what the protocol does. It's a contract for letting a model call your tools without you hard-coding a single one.
May 20, 2026 · 10 min read
DevOpsHow Vercel deploys in seconds
Push to a branch and a URL is live before you switch tabs. Behind it: immutable builds, a global edge cache, and an atomic swap that can't half-deploy.
May 13, 2026 · 10 min read
AI & AgentsHow AI remembers your conversations
Models are stateless. So how does a chatbot recall what you said ten messages ago? It re-reads the entire thread every single time, and that costs more than you'd think.
May 6, 2026 · 11 min read
NetworkingHow DNS finds a website in 20ms
Four servers you've never heard of answer a question you ask thousands of times a day. And four caches in between will happily give you yesterday's answer.
Apr 29, 2026 · 9 min read
Web DevHow JWT authentication really works
A JWT isn't encrypted. Anyone can read it. The magic is the signature, and misunderstanding that one fact is how most auth bugs get shipped.
Apr 22, 2026 · 10 min read