Written for an organization with security specialists across separate disciplines, and exposure that justifies them.
Think of it likeKeeping a locksmith, an electrician, and a fire inspector on staff because the building is big enough to need all three.
In plain English
IG3 is the full catalogue. The safeguards added here assume dedicated expertise in areas like application security, incident response, and penetration testing, so reaching it is a staffing question before it is a control question.
IG3 covers 153 of the 153 safeguards in CIS Controls v8, which is every IG2 safeguard plus the 23 added at this level. Each one below links to a plain-English translation.
Control 1: Inventory and Control of Enterprise Assets