Collisions refer to the interactions between particles (atoms, molecules, etc.) where there is a transfer of momentum and/or energy. These collisions can occur between particles of the same type or different types.
Related terms
Elastic Collision: An elastic collision is a type of collision where kinetic energy is conserved before and after the collision.
Inelastic Collision: In an inelastic collision, kinetic energy is not conserved because some of it is converted into other forms such as heat or sound.