blocks and sections -> what are these and why can't I put blocks in containers

I try and drag a block into a header or other container and it refuses to be moved inside these. Why? Sections seem to be more movable but have their own rule of where you can put them. Again why is this?

Thanks

Did you try a search on the forums here for "inside container" you will most likely find a lot of posts that answer that question :)

Familiarize yourself with the Bootstrap grid system. Certain components cannot be placed inside other components. For example, rows go inside containers. You can't place a container inside a row.

https://getbootstrap.com/docs/4.4/layout/overview/