What does the !! (double exclamation) operator do in JavaScript?

Hello, colleagues! I'm new to JavaScript and came across some strange code. In one project, I saw this construct:\n\n```javascript\nconst isActive = !!someValue;\n```\n\nI understand that `!` is the logical NOT operator. But why write two exclamation marks in a row? What does it even mean? I tried removing one sign — the code broke. I tried removing both — it also didn't work as expected.\n\nI've read that `!!` is some kind of "operator," but I couldn't find it in the official documentation. Is it some trick? Or is it just a bug in the code that everyone copies? Maybe there's a clearer way to do the same thing?\n\nPlease explain in simple terms what this is for, and why it's so popular in the JavaScript community. Preferably with examples to make it clear how it works with different types.