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.
Wall
Fire walls resist spread of fire within or sometimes between structures to provide passive fire protection. A delay in the spread of fire gives occupants more time to escape and fire fighters more time to extinguish the fire. Such walls have no windows, and are made of non-combustible material such as concrete, cement block, brick, or fire rated drywall—and have wall penetrations sealed with special materials. A doorway in a firewall must have a rated fire door. Fire walls provide varying resistance to the spread of fire, some intended to last one to four hours. Firewalls, generally, can also act as smoke barriers when constructed vertically from slab to roof deck and horizontally from an exterior wall to exterior wall subdividing a building into sections. When constructed in this manner the fire wall can also be referred to as an Area Separation Wall.