ISOFIX and LATCH
Standardized anchor points for fitting child seats without relying on the seat belt: ISOFIX in Europe, LATCH in the US, the Universal Anchorage System in Canada.
ISOFIX gives the car two lower anchorages that a child seat connects to, so the seat does not depend on the seat belt alone. In Europe, UN Regulation 14 covers ISOFIX anchorage systems and top-tether anchorages in passenger cars, and UN Regulation 129 covers the i-Size seats that fit them. A third point, either a top tether or a support leg, limits the seat's rotation.
The US system is LATCH: two lower anchors plus a tether anchor, with their location and strength set by federal standard FMVSS 225. Lower anchors carry a weight limit. NHTSA says the seat's label states it; without a label, subtract the seat's weight from 65 pounds. Beyond the limit, reinstall the seat with the vehicle belt. Canada uses the Universal Anchorage System (UAS), and Transport Canada says vehicles made after 2002 have one.
Anchor counts and positions differ by car, so check the owner's manual for your model and match the child seat's approval to your market.
Differs by market
In Europe, ISOFIX anchorages are covered by UN Regulation 14 and i-Size child seats by UN Regulation 129. The US uses LATCH under FMVSS 225, and Canada uses the Universal Anchorage System (UAS). Elsewhere, including Australia, check the anchor points on the specific car. Child seats are approved per system and market.