DAU Professor Matt Ambrose provides a top level description of Acquisition Categories (ACATs) and how they are arrived at and used to manage acquisition programs. Included are weapon system and automated information system categories one through three. Professor Ambrose also explains what makes a system a Major Defense Acquisition Program (MDAP) or a Major Automated Information System (MAIS). The DoDI 5000.02 and Milestone Documentation Identification tool (MDID) are referred to for further exploration of the topic and practical application.