Lock having simplified structure

A lock, comprising:

• a lock core structure, comprising:
• a restriction unit having a passage penetrating therethrough to form a first opening and a second opening on two opposite sides of the restriction unit, wherein an extension wall is formed in the passage to face the second opening;
• a lock core disposed in the passage, the lock core being movable relative to the restriction unit in an axial direction and comprising:
• an end face facing the extension wall;
• and
• an extension portion disposed on one side of the lock core close to the first opening, the extension portion extending under the extension wall toward the first opening and selectively protruding outside the first opening;
• and
• an elastic unit disposed between the end face and the extension wall, two ends of the elastic unit respectively contacting the end face and the extension wall;
• and
• a movable unit selectively contacting the lock core and capable of performing a reciprocal rotation, rotation of the movable unit is linked to axial movement of the lock core;
• wherein the elastic unit releases an elastic force to push the end face so as to drive the lock core to move relative to the restriction unit and away from the movable unit.