  Of the tens of thousands of particle accelerators in operation worldwide, the
vast majority are not used for particle physics, but instead for applications.
Some applications such as radiotherapy for cancer treatment are well-known,
while others are more surprising: food irradiation using electron beams, or the
hardening of road tarmac. The uses of particle beams are constantly growing in
number including in medicine, industry, security, environment, and cultural
heritage preservation. This lecture aims to give a broad sweep of the many uses
of particle accelerators, covering technologies ranging in size from a few
centimetres for industrial electron linacs through to large synchrotron light
sources of hundreds of metres circumference operating as national and
international facilities. We finish by discussing some of the challenges facing
accelerators used in wider society.
