PlayStation Network (also abbreviated as PSN) is an online platform created by Sony Computer Entertainment, and is used on numerous Sony devices, primarily the PlayStation series. A PlayStation Network account is required to use network features, such as online play.
In 2010, Sony released an initially optional premium service, PlayStation Plus. This granted users access to several features such as free games, exclusive content (such as demos and themes), an auto-update feature and a cloud backup service similar to Steam Cloud.
Later, PlayStation Plus was re-introduced as a service somewhat mandatory for online play on the PlayStation 4. Some games do not require PlayStation Plus for online play, or allow restricted access to online features. Only one membership per PlayStation 4 system is required for access to full online play.