How do i unscrew a nut that's isn't moving?

To unscrew a stuck nut, first ensure you have the right size wrench or socket. Apply penetrating oil to the nut and let it sit for a few minutes to loosen any rust or debris. Use a breaker bar or an impact wrench for added torque if needed, and tap the wrench gently with a hammer to help break the bond. If it still won't budge, consider applying heat to expand the metal, but use caution to avoid damaging surrounding components.