HTML 5 Local and Session Storage

I am trying to figure out where browsers that support HTML 5 actually store the data they persist as Session or Local storage.  I assume that, since Session Storage persists only as long as the browser window that created it exists, the data is stored in memory.  Is that a correct assumption?

What about Local Storage?  Since it persists between browser sessions, it must be persisted to disk, but where?  Is there a maximum lifetime assigned to Local Storage?

I did a number of searches and I can find all kinds of information on exactly what these types of storage are but nothing on the mechanics of them

Thanks

Bert