The standard Monopoly board game has eight colored street groups.
The groups run from the two-property dark-purple and dark-blue sets to the three-property light-blue, pink, orange, red, yellow, and green sets. Owning every street in one group gives a player a monopoly, allowing doubled rent on unimproved properties and permitting house construction according to the rules.
Railroads and utilities are purchasable spaces, but they are not colored street groups. This distinction explains why the number of color groups is lower than the total number of property categories on the board.
The group colors are also a major visual part of Monopoly strategy. Players often value orange and red properties because they are frequently reached after leaving Jail, while the dark-blue properties have the highest potential rents. The standard color arrangement is specific to the classic board; themed editions may recolor or rename their properties.