SIS II is a Europe-wide electronic system for alerts on persons and objects, jointly operated by the Schengen States. It contains information on persons wanted by the police or judicial authorities, persons subject to entry bans, missing persons, and stolen property (e.g. vehicles or firearms). SIS II is a key instrument for police and judicial cooperation.

As part of the Schengen framework, systematic checks on persons at the internal borders between Schengen States have been abolished in order to facilitate travel. At the same time, cross-border police cooperation has been strengthened, thereby ensuring and enhancing security and public order within the Schengen area.

SIS II contains alerts on both persons and objects. These alerts enable the competent authorities to identify a specific person or object and to take the necessary measures.

Since 2013, it has been possible to store biometric data such as fingerprints in SIS II. Since the introduction of AFIS (Automated Fingerprint Identification System) in 2018, it has been possible to identify individuals solely on the basis of a comparison of their fingerprints.