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Ask most people what the box with the blinking lights does and they'll say "it's the internet." Fair. But that box is usually doing three or four separate jobs, and once you know which is which, a lot of home network problems (and shopping decisions) start making sense. The modem talks to your ISP Your internet provider delivers service over some kind of line: coaxial cable, a phone line for DSL, fiber, or a cellular signal. The modem's job is to translate whatever comes in on that line into regular Ethernet that a computer understands. That's all it does. It doesn't hand out addresses to…

People use "open source" to mean free, or "the code is on GitHub," or just vaguely good and community-minded. Those overlap with the real meaning, but none of them is it. Open source software is software whose license gives you the right to use it for any purpose, read the source code, change it, and share it, including your changed version. The Open Source Initiative keeps the formal definition and a list of licenses that meet it. The key word is rights. It's not about whether you can see the code. It's about what you're legally allowed to do with it. That distinction matters more than it…

Light in a fiber cable is fast, but it isn't instant. If a website lives on one server in Virginia and you're loading it from Sydney, every request has to cross an ocean and come back. A modern page might need dozens of files (images, scripts, fonts, stylesheets), and all those round trips add up to a page that feels sluggish even on a great connection. You can't make the planet smaller. What you can do is move the files closer to the people asking for them. That's what a CDN is. Content delivery network. It's a company that runs a lot of servers in a lot of cities (they call them edge…

USB-C was supposed to be the one cable to end all cables. And as a plug, it kind of is. It's reversible, it's small, it fits laptops and phones and headphones and monitors. The trouble is that "USB-C" only describes the shape of the connector. It says nothing about what's going on inside the cable, and that's where all the confusion comes from. Two USB-C cables that look identical can be wildly different. One might charge your laptop at full speed, move files fast, and run a 4K monitor. The other might barely charge a phone and transfer data at speeds that were normal a long time ago. Same…

Every endpoint on your app is an open invitation to send requests. Most visitors send a few. Some scripts will send as many as your server can take. Rate limiting is just the rule that says "this many, this fast, and no more." It's one of those features nobody notices when it's there and everybody notices when it isn't. Here's what it protects you from. Brute force on your login page. Without a limit, an attacker can try password after password as fast as your server answers. Even with good password hashing, you don't want to give them unlimited attempts. Abuse of expensive actions. Sending a…

At some point a lot of people decide they're done letting an ad company read their inbox. Good instinct. Then they search "private email" and land in a pile of providers that all promise privacy in slightly different ways, and it's hard to tell what actually matters. So let's walk through the big names and, more importantly, what they can and can't do for you. First, a reality check about email Email was never built to be private. Every message has a sender, a recipient and a timestamp, and the servers involved need that information to deliver it. No provider can fully hide who you talk to…