<%= yield %>

What does <%= yield %> mean that someone can find in the .html.erb file
in the "layouts" directory? Is it just rendering the data to show up on
the page?

Thanks.

Have a look at the Rails Guide on Layouts and Rendering at
http://guides.rubyonrails.org/. It should explain it. If you have
not already done so have a look at the other guides as well.

Colin