Contour is generally a non surgical/makeup enhanced way of defining the face and its features.
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Contouring gives the face enough 'shadow' that makes the face look as natural as possible after makeup application especially the nose (when you 'nose contour') which is the perfect place to show off contour.
Revered makeup artist Wayne Goss once shared easy ways to contour noses, he said for Long Noses; start out contouring on the sides of the nose bridge and then contour around the nostrils so the tip of the nose is downplayed giving off an illusion of a pointed, chiseled nose.
For Broad Noses; contour from the sides (of the nose) starting from the inner corners of the eyes till the end of the nose and blend to achieve a slimmer nose.
Blogger Deola Adebiyi of OmogeMura breaks down easy way to contour the nose and it's a must try out if you are looking to perfect the makeup process.