Check (調べる, Shiraberu?, lit. Examine), entered as "/check" or "/c", is a basic text command in Final Fantasy XI that informs the player of the relative difficulty of defeating the creature in question, or reveals the job, level, equipment, and comment of a player in question.

When a monster is checked, it will be listed as one of the following:

• "Too weak to be worthwhile" (listed as "too weak" in the auto-translator): a creature is significantly below the player's current job level, and will not give the player any experience points for defeating it.
• "Incredibly easy prey": the monster is 11+ levels below the player starting at level 67, but still yields experience points. Because of how experience and aggression mechanics weren't scaled after level 75 cap, you can still get experience from monsters as much as 43 levels below you (63 with Item Level gear).
• "Easy prey": the monster is many levels below the player, but will still yield experience points upon defeat.
• "Decent challenge": the monster is a lower level than the player, but it is still near the player's current level.
• "Even match": the monster's level is exactly the same as the player. There is a good chance that the player will be defeated if taking on an even match solo.
• "Tough": the monster is a small number of levels above the player.
• "Very tough": the monster is many levels above the player.
• "Incredibly tough": the monster is substantially higher-leveled than the player.
• "Strength is impossible to gauge!": the monster's strength is not revealed. This usually indicates that the monster is a notorious monster, or is a target involved in a certain event, such as the Nyzul Isle Investigation. Monsters that are impossible to gauge may actually be a much lower level than the player, but that information is not revealed.

Additionally, monsters that aren't "impossible to gauge" can also be shown to have high or low defense and evasion (e.g. "it has low evasion but high defense"). If it has about the same stats as you, it won't display a message.