What does "set this as the default description" do?

[Sergi]

When editing the details of a book, what does the checkbox "set this as the default description" under description actually do?

This is in the context of the English edition of book whose original edition in Spanish.

[Monika]

If there is more editions of this book and if one (or more, doesnt matter) of these editions does not have a description then the default one will be shown in description box