Redlining is an illegal discriminatory practice where lenders refuse to lend money or give credit to borrowers based on race, and geography.  This form of institutional racism became known as redlining because banks would draw a red line around a neighborhood which marked the area where they would not lend money to anyone in the red area.  These areas were usually poor communities mostly filled with blacks and other minorities and severely stunted the growth of these communities.

To read more about redlining and truly understand it's damaging effect, see 10 Corporate and Government Policies that Unfairly Punish Black Men