What is the left hand rule for magnetism and how is it used to determine the direction of the magnetic field in a current-carrying conductor?

The left-hand rule for magnetism is a way to determine the direction of the magnetic field around a current-carrying conductor. To use this rule, point your thumb in the direction of the current flow (from positive to negative), your index finger in the direction of the magnetic field, and your middle finger will then point in the direction of the magnetic field lines. This rule helps to visualize and understand the relationship between current flow and magnetic fields in a conductor.