Tensile strength is defined by the maxima of a stress-strain curve and typically indicates when the test sample necks down. There are 3 common definitions of tensile strength:

Ultimate tensile strength - The maximum stress a material can withstand. It is the maximum stress on the stress-strain curve (see item 1 above)

Tensile yield strength - The stress at which material strain changes from elastic to plastic deformation (see 2 above).

Tensile Break strength - The stress coordinate on the stress-strain curve at the point of rupture (see 3 above).

Tensile tests are the most common material strength test and measure properties such as yield strength, modulus, ultimate tensile strength, poissons ratio, reduction of area and elongation to failure.