Think about it. Have you every stopped to wonder how you might define the word behavior?

Paraphrasing one prominent textbook on behavior analysis, a behavior is:

…an organism's interaction with its environment that is characterized by detectable movement of some part of the organism in space through time, and that results in a measurable change in the environment. (Johnston, J. M. & Pennypacker, H. S. (1980), Strategies and tactics for human behavioral research. Hillsdale, N.J.: Lawrence Erlbaum, P. 48.)

A key concept here is that behavior is an observable movement by the organism. When we talk about behavior we need to remember that the most useful information concerning behavior, from the standpoint of behavior analysis and teaching, contains observable and measurable descriptions.

Everyday language is filled with imprecise speech that often leads to incorrect interpretations and confusion around behavior. We say that a person was "unhappy" earlier in the day even though all we observed was an intense look on the person's face during a study time. We talk about a child who has tantrums as "angry" at his teachers or "rebellious."