Check (Japanese:チェック Check) is a command in the Mother series.
Outside of battle
The Check command is used to look at objects that can't be spoken to. In Mother, it is accessed by pressing the A button to open the menu and selecting it. In the Mother 1+2 port and EarthBound, the L button acts as a shortcut to both talk and check. In Mother 3, it is no longer an option on the menu; instead, the L and A buttons both check objects and talk to people. When an object can be both checked and spoken to in the Mother 1+2 version of Mother, such as the Dragon, the game will default to the talk command.
The Check command is also a battle command in Mother. Using the check command in battle will reveal the enemy's Offense and Defense stats, their weaknesses and resistances, and, in the prototype and Mother 1+2, a description of them. In EarthBound, this usage was replaced with Spy, which in the Japanese version, is also named Check; however, this skill can only be used by Jeff. In Mother 3, it was replaced with Boney's Sniff.
A battle screen from the unreleased EarthBound 64 indicates that Check was going to regain its in-battle usage from Mother, rather than being replaced by Boney's signature ability as in the final version; additionally, it shows Flint using it, indicating that any character could use it.