This document provides an overview of the IUCN protected area categories system. It discusses how IUCN developed 6 categories in 1994 to classify protected areas based on management objectives. This system influenced conservation planning and policy. IUCN revised the guidelines in 2008 following consultations, keeping the 6 categories but clarifying definitions and guidance. The categories are used globally to assess and plan protected area networks, while governance types describe protected area management responsibilities. IUCN continues working to build capacity on properly applying the categories system.