Define deformation, Equilibrium, compatibility in frame structure?

DEFORMATION IS THE ALLOWABLE  MOVEMENT IN X,Y,Z FOR AN ELEMENT TO HAVE UNDER WORKING LOAD AND BE ABLE TO GO BACK TO ITS ORIGINAL SHAPE AND FORM WITH NO DEFECTS , THAT'S WHY WE CHECK FOR DEFLECTION.

EQUILIBRIUM AND COMPATIBILITY IS THE WAY YOU SOLVE AND GET THE STRESS FOR THE ELEMENT ALSO YOU NEED TO KNOW THE TYPE OF THE ELEMENT DETERMENT OR NOT