Energy and entropy, two quantities that can define the character of a system are formulated into free energy in thermodynamics. Energy is a tangible concept as it is measurable that particles of a system attract and repel each other owing to their so-called fundamental forces between subatomic particles such as electrons and protons. Knowledge of the interaction energies between the constituents of a system is insufficient to fully predict the behavior of a system, and one must know the entropy to have a precise prediction. In contrast to energy, it is intuitively difficult to understand entropy. The constituents of a system, particles, bear random Brownian motions in a given temperature -temperature is a measure of the kinetic energy of particles which is exerted on particles of the system by collision with particles of a heat reservoir and other possible surrounding factors. A single particle with no energy at absolute zero Kelvin remains motionless in a phase space until a collision moves it to a particular direction in a stochastic manner. Each particle has infinite accessible microscopic states to possess in a continuum space with time's arrow. Here, we define each particle that can select a microscopic state for every individual displacement of kT -one bit of information -after a collision, one degree of freedom . Therefore, in a system with n particles, the total of n degrees of freedom are available for random displacements at the microscopic level of that system . These collective random motions of particles in a system at a given temperature have two manifestations from two perspectives. While we studied one of these manifestations, we find it important to explain briefly both of them to emphasize the contribution of entropy in the behavior of a system. In this regard, first, we discuss the effect of a mechanical external force on a system with certain initial entropy at an initial temperature. Then we discuss the interior configuration of a system influenced by the entropy of that system at a given temperature.