TECH BASICS
Open Source
Software anyone can see, use, and help improve — for free.
The simple version
Open source software is code that anyone can view, use, modify, and share, usually for free. Instead of one company keeping the code secret, it's out in the open, and often built by thousands of volunteers and companies working together.
For example
Linux runs a huge share of the world's servers and phones (it's the core of Android), and it's completely open source. Same with tools like React, the library used to build many apps and websites you use every day.
Go deeper
Open source doesn't mean "no business model." Companies build paid products, hosting, or support services on top of free open-source code — that's how many successful startups operate. "Contributing" to open source (submitting fixes or features) is also a common way developers build a public track record before they've had a job.
Why it matters
A huge amount of the modern internet — from your phone's operating system to the tools engineers use every day — runs on open source. Understanding it helps you see how software actually gets built, and it's a common way people break into tech without a traditional resume.