This skill is used to spot stealthed characters.
Classes: Druid, Monk, Ranger, Rogue, Spirit shaman; Arcane archer, Arcane trickster, Assassin, Duelist, Dwarven defender, Invisible blade, Neverwinter Nine, Red dragon disciple, Shadow Thief of Amn, Shadowdancer
Requires training: No
Check: The spot skill is always active and used primarily to detect characters or creatures who are hiding. Typically, your spot check is opposed by the hide check of the creature trying not to be seen. It is also used to spot those who would use sleight of hand to deceive a character, and to avoid the effects of Feint.
Special: A ranger gains a bonus on spot checks when using this skill against a favored enemy; An elf or aasimar has a +2 racial bonus on spot checks; A half-elf or gray dwarf has a +1 racial bonus; a druid receives +2 to spot in outdoor or wilderness areas due to nature sense.
Use: Automatic (enhanced when in detect mode).
As of 1.22 checks are made 6 times a round by Elves (Keen Senses) and once a round by other Races.
DnD 3.5 comparison
Spot is also used to detect someone in disguise, and to read lips when you can't hear or understand what someone is saying.