Why did Putin invade Ukraine?

The history of Putin's invasion of Ukraine is extensive. Here is a news article from CNN that explains what led to this war and what Putin is trying to achieve: https://www.cnn.com/2022/02/24/europe/ukraine-russia-conflict-explainer-2-cmd-intl/index.html

Here's a brief history of Putin and his past from History.com: https://www.history.com/news/vladimir-putin-russia-power