There are a variety of test methods used to indicate the "strength" of joints bonded with adhesives. These tests have been developed for a variety of needs ranging from the apparently simple, such as stickiness or "tack" of pressure sensitive adhesive, to more complicated ones, such as impact resistance or environmental durability of adhesive joints on automobiles.
The measured results from these tests have significant importance. They influence the selection of an adhesive system, they are used to optimize formulation and processes, and generally they are the "language" used to communicate among those active in the field.
There is a significant problem, however, with adhesive testing -- the performance of adhesive systems is never solely due to the material properties of the adhesive. All too often the test results are a function of the test rather than the adhesive being tested. Often this is due to viscoelastic nature of adhesives, which is very dependent on strain rate and other test parameters.