How do I lead teams I don't manage?

Leading teams you do not control feels impossible when your instinct says leadership comes from authority. But most real influence has never come from the org chart. It comes from clarity, trust, and being the person who makes the shared work easier. You have more power here than the title suggests, just a different kind. People follow an engineer across team lines when that engineer reliably reduces their confusion and their risk. If you become the one who sees the whole technical picture and helps others succeed inside it, they will look to you without being told to. That is earned, not granted, and it is slower, but it is also more durable. Start by helping one person on another team solve something that matters to them, with no angle of your own. Being genuinely useful first is how influence begins when you have no authority. Lead by making others better, and the leading takes care of itself.