In plain terms. GSAR is the General Services Administration's supplement to the FAR. GSA runs government-wide acquisition vehicles, so its rules reach far beyond GSA itself.
Who it applies to. Contractors on GSA Schedules and government-wide contracts, plus those serving GSA directly.
What it requires. Follow the FAR, then GSAR additions. Because GSA vehicles serve the whole government, contractors must meet the FAR cyber baseline and any order-level security terms agencies add when they buy through GSA.
Why it matters. GSA's vehicles are a primary path to federal sales, so its rules — and the security terms riding on individual orders — affect a wide swath of contractors.
Citation. GSAR, the General Services Administration Acquisition Regulation supplement to the Federal Acquisition Regulation (FAR), codified in the FAR System at Title 48 of the C.F.R.