The grounds pretty much include anything outside of Hogwarts, but still a portion of the campus. This does not include, however, the Forbidden Forest. RPs set there need to be in the forum created specifically for that area.

Any RPs that move into the castle should literally MOVE to the castle. Wrap up the one on the grounds and make a new board there. Simple, right?

If you start a RP in the wrong place, PM the mule and it'll be moved/deleted as needed. No need to panic!

Areas on the grounds include:

xxxxxQuidditch Pitch -- A large field designed specifically for Quidditch. Cheer for your favorite house team!
xxxxxGreenhouses -- The Herbology classes are taught here.
xxxxxTraining Grounds -- Want to learn to fly? This is where the class is taught to first years.
xxxxxThe Lake -- Located to the south of the castle, this large body of water is home to the giant squid and mermaids.
xxxxxGamekeeper's Hut -- This small hut is located near the forest. It's alive with the sounds of wildlife.

And the grounds in general. xD Enjoy your fun in the sun while it lasts! The grounds are covered in snow come winter.