Valley fold
A valley fold is a fold where the paper bends toward you, so the crease sinks down like a valley with the two sides rising on either side of it.
To make one, lift part of the paper, bring it over the rest along the marked line, line up the edges or corners the diagram shows, then press the crease flat from the middle outward. In diagrams a valley fold is drawn as a dashed line, usually with an arrow showing which way the paper travels.
The most common mistake is creasing before the edges are aligned. Hold the points in place with one finger, check them, and only then run a fingernail along the fold. Creasing from the center outward also stops the paper from shifting.
