Obligations are requirements arising from a person’s situation or circumstances (e.g., relationships, knowledge, position) that specify what must or must not be done for some moral, legal, religious, or institutional reasons. For example, students may have an obligation see their advisor on or before Registration Day, simply because this is one of actions students in a particular institutional context are asked to perform. It can also be argued that persons, insofar as they are moral beings, have an obligation to keep their promises, because this is one of things that is required for the act of promising. Notice that usually statements of obligations specify what acts are required or forbidden without reference to the consequences of performing the act (except in so far as these consequences are a part of the characterization of the act itself).

Obligations can be more or less specific. That drivers are obligated to obey the traffic rules is much more specific than "Engineers have an obligation in their work to ensure the public safety." The second obligation names a responsibility that engineers have to achieve a certain end, namely safety of the public, but fails to specifying what specific acts they should or should not perform in order to ensure safety.

A legal obligation is one that specifies what types of actions are permitted, forbidden, or required with certain state-enforced penalties attached for failures to comply.