Foundation: A synthetic brush. Can also be used for applying cream blush.
Concealer: A narrow, synthetic brush with a slightly tapered edge.
Powder: A big, soft natural-fiber brush.
Contouring: A soft brush with a flat, angled edge. Also used for bronzing.
Blush: A soft medium-full round brush. Natural fiber is best.
Eye Shadow: A tapered, flat brush that is good for blending.
Fan Brush: A light brush that is great for highlighter. It’s also good for brushing away loose eye shadow.
Eyeliner: A narrow, angled brush for applying gel liner or shadow as liner.
Eyelash and Brow Comb: The side with the small, plastic comb is used for removing mascara clumps from lashes. The bristled side is for grooming eyebrows.
Eyebrow: A firm, angled brush used for filling in eyebrows with brow powder. Go for something with coarser bristles.
And never underestimate the power of the original makeup brush—your fingertip. Because of the heat of your skin, fingers make unbeatable blending tools. For covering under eye circles, I like to use a clean ring finger (the ring finger applies the least amount of pressure) to blend away the edges of the concealer.
Source: http://laurenconrad.com/blog/2013/03/beauty-school-makeup-brush-guide-uses-types/