This first course in mechanics of deformable bodies introduces the four concepts - Force, stress, strain, displacement and the four equations that connect them, namely equilibrium equations, constitutive relation, compatibility condition and strain displacement relation.Systematic procedure to solve problems of engineering interest is outlined. In particular, force and displacement relation of structural elements subjected to uniaxial stress, bending, twisting and inflation is studied. Estimation of possible modes of failure of these structural elements and the failure load is outlined.