What is this "2026 Iran war" people keep talking about?

It is a real war between the US and Israel on one side, and Iran and its allies on the other. It started at the end of February this year. The first attack was big — it even killed Iran's top leader, Ali Khamenei. After that, Iran fired back with missiles and drones. Many countries in the region got pulled into this fight, so some people are calling it the "Third Gulf War."