Blend color in photoshop

[RTW1]

The blend modes in Photoshop, this is a very simple guide it does take a lot of time before they come automatic to you.
1 will darken the layer below
2 will lighten the layer below
3 will add some contrast to the layer below
4 will invert the colours to the layer below
5 will effect colours etc. to the layer below
6 is the Opacity or strength of the effect.
A real life example that I have used thousands of times is to duplicate the background layer, then change its Blend Mode to Soft Light to increase contrast in a natural way.