Warders are traditionally trained at the White Tower so that, once their training has been completed, they may serve the Aes Sedai as bodyguards. In their training, they are brought to a pinnacle of swordplay; man for man, Warders are historically considered to be the finest fighters in the land. They are highly recognizable for their "color-shifting" cloaks, which are made of fancloth created by a ter'angreal recovered from the Age of Legends, and provide chameleonic camouflage for their wearers.
The Warder bond has distinct benefits for both parties. The bonded party (the Warder) gains greater stamina and physical prowess, a greater capacity to resist evil, and greater resistance to injury. The Aes Sedai, for her part, gains a bodyguard, confidant and ally-in-schemes who is intrinsically linked to her and whose behavior can be controlled (to some extent) through the bond. She is also able to draw on the warder's strength if needed. Both parties are able to sense the other's general location, physical well-being and, to some extent, emotional state. Of course, this in itself can cause problems, should one party or the other become intoxicated or involved in romantic liaisons. Death is also a major occupational hazard; if one member of the bond is killed, the other suffers extreme emotional trauma, to the point that most orphaned Warders lose all will to live, and often throw away their lives in a berserker rage.
Whether by custom or law, all Warders are male; the only (known) woman Warder is Birgitte Silverbow Trahelion, bonded to Elayne Trakand, who bonded her because doing so was the only way to save Birgitte's life. Female-female bonding is more empathic than male-female bonding: Birgitte finds Elayne's emotional state contagious, and vice versa. Aes Sedai are capable of bonding several Warders at once, though only the Green Ajah make a habit of it; generally, men are bonded one at a time, as opposed to several through the same bond, and it is unknown if Warders bonded this way have any extrasensory awareness of each other. Three women (Elayne Trakand, Elmindreda Farshaw and Aviendha of the Nine Valleys sept of the Tardaad Aiel) have recently bonded a single, communal Warder (their mutual lover, Rand al'Thor); all three women hold the bond and are connected to him, though not to each other. It is not known if the converse, a single bond used to hold multiple Warders, is possible. Women who cannot channel (Min Farshaw) can hold Warder bonds, though still she required her channeler friends to create it. It is possible for two separate women to bond the same man as Warder on separate occasions, without interfering with each other's bonds: al'Thor, at the time of his bonding to his three loves, had already been bonded (against his will) by Alanna Mosvani in a fruitless attempt to control him. Finally, Warder bonds can only be dissolved by the holding Aes Sedai; the Warder himself can be kept against his will.
As of the later books in the series, Asha'man have discovered their own form of the Warder bond using saidin and have begun bonding women as Warders. In the beginning, married men bonded their wives, primarily for the benefit of being able to stay in contact with them through the bond, but recently Asha'man have also bonded a small number of captured Aes Sedai, much to the consternation of the White Tower. This form of the bond permits the use of Compulsion to control the captive Aes Sedai. In addition, three Asha'man (Damer Flinn, Jahar Narishma, and Eben Hopwill) have been bonded as Warders by Aes Sedai, and in Knife of Dreams, Mazrim Taim grants permission to Aes Sedai to bond his Asha'man. The fact that both parties can channel has had no (known) effect on the Warder bond, but there has been speculation that male channelers universally cannot be controlled the way normal Warders can.