An orbit is the circular or dumbbell shaped motion that the electrons follow around the nucleus. Much like the planets orbiting the sun
Electrons are essential components of an element and decide its reactivity and bonding. They have their own unique properties known as quantum numbers which makes them all unique, existing in a number of sub orbitals around a nucleus.
The work of J.J Thomson’s student, Ernest Rutherford, led to the discovery of the Proton. Working with alpha particles fired at a piece of gold foil it was observed that instead of passing straight through it was scattered. Suggesting there was something large in the centre of the atom.