A humanoid robot is, in the strictest sense, a robot built in roughly human form: two legs, two arms, a head where the sensors live, a torso between them. That's the minimum bar. Everything else — what the robot can do, what it's for, whether it's a "general purpose" machine or a special-purpose one — is opinion and marketing.
Why does this matter? Because the loose definition lets companies call almost anything a humanoid. A wheeled torso with two arms is sometimes claimed as one. So is a bipedal robot with no arms. The reason editorial sites like this one care is that the definition determines what you're comparing — and a comparison only means something when both sides are playing the same sport.
For our purposes, a robot counts as humanoid if it has all three of: two legs (or a clear plan to walk on two legs in shipping configuration), two arms with manipulators of some kind (hands or grippers), and a vertically oriented body. Animatronics are out — they don't manipulate the world. Quadrupeds are out — they have four legs. Robotic arms on wheeled platforms are out — no legs.
This is editorial, not industry consensus. The IEEE doesn't ratify these definitions. But the working line has to be drawn somewhere, and drawing it like this makes the comparison table on each robot profile actually mean something.
Why are humanoids interesting? Because the world was built for humans. Doorknobs are at a certain height. Stairs are a certain rise. Tools are sized for human hands. A robot that fits the human form factor can, in theory, use any tool a human can — without retooling the environment. That's the bet. Whether the bet pays off depends on whether the technology can actually meet the form factor's demands. Most of this site is in service of answering that question, robot by robot.
The opposite bet — change the environment, not the robot — is what powers warehouse logistics today. Amazon's fulfillment centers are built around wheeled robots and conveyor belts because retrofitting the environment was easier than building a humanoid that could navigate a human one. The argument in favor of humanoids is that you cannot retrofit every environment — especially homes, hospitals, and small factories. The argument against is that you mostly don't need to.
The next ten years will determine which argument is right. This site is trying to be honest about what we know so far.