Right-hand twill describes the direction of the diagonal line created by a twill weave: in right hand twill, the line runs from the lower left to the upper right of the fabric as you look at it. This is the most common weave direction used in denim production worldwide.
In practice, right hand twill denim tends to have a smoother, flatter surface than left hand twill, and it is generally considered slightly more resistant to twisting after washing, since the weave direction and the natural twist of most spun yarn work together rather than against each other. This makes it a dependable, widely available choice for everyday jeans.
Most mass produced jeans use right hand twill denim, while some traditional and selvedge focused makers favor left-hand twill or broken twill for a different hand feel and fade pattern. See our denim guide for how weave direction fits into overall fabric character.