The manipulation of matter with electromagnetic radiation is a capacity that has been known for over
a century. However, the prominence of such optical effects only grew rapidly following the invention
of optical tweezers in the 1980s. While both the original theory and the early trapping techniques
are based on the radiation force, optical tweezing uses the gradient force. This paper aims to
differentiate between these two clearly distinct types of optical forces, which are sometimes
confused in the literature. We also discuss three completely separate forms of optical torque that
can be applied to a particle, also due to an electromagnetic field. These involve the transfer of
either spin or orbital angular momentum from the beam to the particle, depending on the character of
the light, or the often overlooked alignment effect that can act on a cylindrical particle due to a
gradient force.