Its source is Yochana, a Hebrew name meaning "God's grace."
The Hebrew Yochana was translated into Latin as Joanna or Johanna. Over time these developed into the Old French Jehan(n)e. At various points this string of ancestors spun off many modern variations that have enjoyed a great deal of popularity.
Most of them share the quality of simplicity. Whether we call to mind the fictitious Jane Q. Public or the legendary Joan of Arc (Jeanne D'Arc in French), these names seem to emerge from the heart of the people.