Historically, they were often called wing-forwards, although this name had a more specific meaning in New Zealand when they used a now-archaic scrum formation.
Flankers are the position where the player should have all-round attributes: speed, strength, fitness, tackling and handling skills.
The blindside flanker has the job of stopping any move by the opponents on the blind (or 'narrow') side from a scrum.
Blindside flankers are often responsible for cover defence from set pieces and may play a more physical role at the line-out, where they may well be used as a jumper.
Most countries prefer a quicker openside flanker with the ability to get off the scrum quickly so that he can scavenge for the ball.
For example, Scotland flankers Finlay Calder and John Jeffrey played left and right, rather than open and blind.
French teams tend not to make a distinction between the two roles, and their flankers also usually play left and right rather than open and blind: thus, Serge Betsen often wore the number 6 but would pack down on either the open or blind sides of the scrum, and will often harass the opposition fly-half in the manner of an openside; like Calder and Jeffrey for Scotland, Betsen and Olivier Magne formed an outstanding left-right partnership for France.