Mechanics is a branch of physics which looks at objects that are moved by forces (including other bodies, or forces of nature).
The discipline has its roots in ancient Greece where Aristotle studied the way bodies behaved when they were thrown through the air (e.g. a stone). However it was Galileo, Kepler and especially Newton who laid the foundations for much of the so-called Newtonian mechanics we know today.
A person working in the discipline is known as a mechanician.