Also known as a turn signal on an automobile, which, although is a useful tool in alerting the public to your turning actions while driving, especially in cases where your turn affects the flow of traffic, seems (by most drivers) optional and almost unnecessary in driving today. I would need several more hands to count on them the number of times someone does not use his/her blinker when it should be used, during a single drive home from work.

See also: turn signals