the energy in a system arising from the relative positions and interactions of its parts is known as internal energy.
						

							
internalenergy is defined as the energy associated with the random , disordered motion of molecules . 
it is separeated in scale from the macroscopic ordered energy associated with the moving object . 
it refers to the invisible microscopic energy on the atomic and molecular scale . 
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Internal Energy in a system is just the sum of all energies(including interactions, oscillations, heat generated) in that isolated system.
						

							
In thermodynamics, the internal energy of a system is the energy contained within the system, including the kinetic and potential energy as a whole. It keeps account of the gains and losses of energy of the system that are due to changes in its internal state
 
 
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							The sum of all the energies present in a system is called internal energy.It can be kinetic and potential energy or the energy required to creat a system.
						

							
INTERNAL ENERGY IS DEFINED AS THE SUM OF ENERGYS OF INDIVIDUAL PARTICALS IN A SYSTEM.
IT CAN BE KINETIC ENRGY OR POTENTIAL ENERGY ACUIRED BY INDIVIDUAL PARTICLE.
 
						

							Internal energy is basically the sum of all types of mechanical energies of all the particles due to its physical state. In mechanical terms there might be kinetic energy, potential energy, vibrational energy etc. But  for an ideal gas system only K.E. remains. In thermodynamics it is a state function.
						

							The energy posseses by the internal  particles of any object is called internal energy.  It cosists of potential and kinetic energy.