Why this lesson

Binary search is the algorithmic equivalent of “measure twice, cut once.” It’s fast, elegant, and—if you get the boundaries wrong—spectacularly off by one. You’ll see it in interviews constantly because it tests careful thinking, not just speed.

Today we’ll master not just vanilla binary search, but its many variations and the edge cases that trip up even seasoned devs. By the end, you’ll wield it confidently in arrays, on answers, on floats, and even in rotated lands where nothing is quite sorted but still somehow is.