Fawn: This color varies from light tan to mahogony. 

Brindle:  This is a fawn dog with black stripes.

Reverse Brindle:  This is a black dog with fawn stripes.  Reverse of the regular brindle.

White:  This is an all white boxer, but can have patches or tan or brindle on one or more places.

Check:  This is a term for a brindle or fawn dog that has approximately 1/3 to 2/3's white.

Black:  This is a term for a sealed brindle.  This is when the brindle stripes are so tight there is no apperance of a stripe.