What is "loop jump"

The Loop jump is a figure skating jump that takes off from a back outside edge and lands on the same backwards outside edge. For a jump with counterclockwise rotation, this is the right back outside edge. It is named from its similarity to the loop compulsory figure. The invention is widely credited to Werner Rittberger, and the jump is also known as the "Rittberger" in Europe. However, evidence exists that it may have been first done as early as the 1880s.