The term ‘behavior’ is used ubiquitously in engineering. It refers roughly to the way technical artifacts ‘behave’ in a given or hypothetical situation, and plays a pivotal role in specific design methodologies since it allows connecting descriptions of the physical structure of technical artifacts to descriptions of their technical functions. However, behavior does not have a precise meaning: engineers use the term loosely and when attempting to pinpoint it, end up with incompatible characterizations. Here we formalize the different notions underlying the engineering usage by providing a uniform framework in which they can be related. This framework lays also a conceptual basis for a precise characterization of the notion of technical function in engineering. Our approach develops within the DOLCE ontology and introduces behavior as a new type of individual quality that relates a technical artifact to the event to which it participates. Starting with this assumption, one can distinguish actual, possible and general behaviors of an artifact (token). We add a few more definitions to capture more specific aspects and show their role in capturing engineering usage.