Tag skill

Tag skills are the player character's specializations. At the start of every Fallout game except for Fallout 4 and Fallout 76, the player chooses three Tag skills which will be their character's specialties throughout the game. The Tag! perk allows one to pick an additional, fourth tag skill later in the game.

In Fallout, Fallout 2 and Fallout Tactics, tagged skills increase at double the rate of an untagged skill (i.e. One skill point translates to a 2% increase in the skill). In Fallout 3 and Fallout: New Vegas however, a tagged skill only gives a 15 point boost.

Tag skills are a vital part of the Fallout universe because they essentially dictate what type of character one will play. A fighter will tag combat skills whereas a diplomat may choose speech, barter and science. A well-rounded character usually includes at least one diplomatic and one combat skill.

Tag skill bonuses
Tagging skills also provides an immediate benefit to one's starting equipment in Fallout, Fallout Tactics and 'Fallout: New Vegas'.

Fallout starting equipment

 * 1x Colt 6520 10mm pistol
 * 48x 10mm JHP
 * 1x Knife
 * 2x flares
 * 4x stimpaks

Fallout Tactics starting equipment

 * 1x MP5 H&K
 * 48x 9mm ball
 * 1x Happy Pie
 * 1x Classic Nuka-Cola
 * 1x stimpaks
 * 1x Midwest Brotherhood leather armor

Fallout: New Vegas starting equipment
After completing the tutorial, every character gets:
 * 4 stimpaks
 * 18 caps
 * 6 bobby pins
 * possibly one ranged weapon (9mm pistol is default if no weapon skills are selected) or one hand-to-hand weapon.

Behind the scenes
At one point, it was planned for Fallout 3 ' s tag skills to give double the points, the same as the previous games.