Paywall
A paywall is a method of restricting access to content via a paid subscription. Beginning in the mid-2010s, newspapers started implementing paywalls on their websites as a way to increase revenue after years of decline in paid print readership and advertising revenue. In academics, research papers are often subject to a paywall and are available via academic libraries that subscribe.
Firewall (construction)
Firewalls can be used to subdivide a building into separate fire areas and are constructed in accordance with the locally applicable building codes. Firewalls are a portion of a building's passive fire protection systems.