A formal inquiry or systematic study.

Subtypes
Investigation (Legal) – One of the skills of detectives, police officers, and lawyers. This type of investigation is conducted within the frame work of a system of governance and laws, usually with the goal of keeping people within those laws.

Investigation (Tracking) – One of the skills of hunters. This type of investigation involves the tracking of footprints and other signs left by a quarry. Typically coupled with a Hunting skill.

Investigation (Magical) – This skill involves the scrutiny of magical beings and objects, and the magical energies around them. This is often both a method of studying and tracking.

Investigation (Social) – This skill involves the interrogation, subtly or overtly, of a person or persons, typically with the goal of acquiring information that they know.

Investigation (Research) – This skill involves the systematic, often scientific, study of a wide range of concepts, typically aided by a wide variety of documents.