Ripe olives, or black olives, are picked at full maturity and come in shades of purple to brown to black. Most black olives sold in stores though are not ripe, they're green olives which have been chemically treated so that they are black.
Olives come from Olea Europea, a small tree. Olives are the fruit of the olive tree. 90 percent of harvested olives are turned into olive oil, while the rest are sold as table olives. Table olives are classified into 3 groups: green olives, turning color olives (semi-ripe) and ripe olives.