"Law" is the system of rules created and enforced through social or governmental institutions to regulate behavior.
Professionals of "Law" include Thomas Hobbes, Thurman Arold, Glanville Williams.
Some subfields in "Law" include legal theory, legal methods, legal systems, legal institutions.
Why study "Law"? pursue a career in the legal system, understand society as a whole, gain insight into the workings of the justice system.