I am trying to understand what a container is and how its used in relations to like an HTML box?

What's the difference, how is it structured/put together.

I have been reading the admin guide page 176, it tells me what I should do to implement it but just trying to get the 50,000 foot view to understand how they work and what they are for?

I am trying to figure out if there is  a way to set up my dnn site so that there is a standard template adn only allow out publishers access to the content on a container, so they don't mess up or have to mess with the templates or other modules, like a simple html box they just update, so the page looks the same and all they are doing is adding in text. Is that possible? Can I use containers for that?

Thanks!