Basic Technique "mountain fold"

This is origami's basic for origami's newcomer.
"Mountain fold" is called "山折り(Yama Ori)" in Japan.Mountain is "山(yama)".
Often case, "mountain fold" is shown a dotted line like this.

You may encounter direction like this.
"Fold and unfold."

Then, you should fold below.
1. Turn paper over.

2. Valley fold and unfold.
If you don't know "valley fold", please read my old post Basic technique "valley fold".

3. Turn paper and complete.

Left paper is "valley fold", right paper is "mountain fold".

Valley fold's reverse is mountain fold.