The process that is characterized by the movement of particles from the area of high concentration to the area of low concentration across the plasma membrane without the use of energy is called PASSIVE TRANSPORT.
When it comes to movement of particles into cells, there are two basic types of transportation, these are active and passive transport. The active transport system needs energy in form of ATP to move the particles across the cell membranes while the passive transport system does not require energy. The rate at which active transport occur usually depend on the permeability of the cell membrane. There are four examples of passive transport, these are: simple diffusion, facilitated diffusion, osmosis and filteration.