Subjectivity is a central philosophical concept, related to consciousness, agency, personhood, reality, and truth, which has been variously defined by sources. Three common definitions include that subjectivity is the quality or condition of:

• Something being a subject, narrowly meaning an individual who possesses conscious experiences, such as perspectives, feelings, beliefs, and desires.
• Something being a subject, broadly meaning an entity that has agency, meaning that it acts upon or wields power over some other entity (an object).
• Some information, idea, situation, or physical thing considered true only from the perspective of a subject or subjects.

These various definitions of subjectivity are sometimes joined together in philosophy. The term is most commonly used as an explanation for that which influences, informs, and biases people's judgments about truth or reality; it is the collection of the perceptions, experiences, expectations, personal or cultural understanding, and beliefs specific to a person. It is often used in contrast to the term objectivity, which is described as a view of truth or reality which is free of any individual's influence.