What technique is commonly used to shape the free edge of nails?

Filing is the technique commonly used to shape the free edge of nails. This process involves using a nail file to carefully remove material from the tip of the nail, allowing for precise shaping and smoothing. It helps achieve a desired length and contour, and also allows for the adjustment of the nail's shape to suit personal preferences or trends.

This method is preferred because it provides control over the length and shape of the nail without causing damage, unlike methods that may involve cutting or harsh treatments. Filing can create various shapes, such as square, oval, or almond, depending on the angle and technique used.

While buffing helps to smooth and shine the nail surface, trimming refers to cutting the nail, which is not typically used for shaping. Soaking is a technique that can prepare the nails for treatment but does not contribute to shaping the free edge.