what's a vertical top bar hive?

Hello David,
I read the summary of your book, it sounds interesting. Can you explain what you mean by "a vertical top bar hive?" I have seen a Kenyan Hive, is that the same thing? What benefits does using the top bar have over the traditional hive?

a Kenyan hive is an example of a horizontal top bar hive: expansion of the nest takes place horizontally.

vertical top bar hives superficially resemble the more common frame hives like Langstroths and Nationals, but use top bars instead of frames. management is also rather different than in frame hives.

here's a picture from David's website:

A great example of a vertical top bar hive is the Warre hive.