A paywall is a method of restricting access to content, especially news, via a purchase or a paid subscription.[1][2] 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, partly due to the use of ad blockers.[3] In academics, research papers are often subject to a paywall and are available via academic libraries that subscribe.[4][5][6]