Step (1):- explanation-
Stress :- When we try to deform anybody by applying any force, due to an elasticity of a reaction force is created in the body. This reaction force tries to regain the shape of body against the applied external force. This reaction force per unit area is known as - Seeress.

Steps = F / A

Strain :- Due to effect of external applied force, there is a relative displacement between the various parts of the body. Thus body changes its shape or volume. This deformation is known as - strain.

$\text{ Strain }=\frac{\mathrm{\Delta \ell }}{\mathrm{\ell }}$