In December 1996, two non-EU states, Norway and Iceland, signed an association agreement with the countries that signed the Schengen accession agreement. Although this agreement never entered into force, the two countries were part of the Schengen area following similar agreements with the EU.  The Schengen Agreement itself was not signed by non-EU states.  In 2009, Switzerland officially concluded its accession to the Schengen area by adopting an association agreement by referendum in 2005.  The Schengen Agreement includes two separate agreements that were ratified in 1985 and 1990 respectively. Between them, they abolished border controls and greatly facilitated transit through Europe. The two individual agreements stipulate that the two Schengen agreements have been a major step forward for transport in Europe. Queues would often be one kilometre long and wait for border patrols to sign them, but the agreements helped to stop them. Today, people can enter neighbouring countries without having to present any form of identity card. Of course, airlines always require you to show it for security reasons, but border controls are much easier to navigate and don`t even exist in some cases.
The Schengen Agreement does not affect the right of EEA citizens to live and work in other EEA countries. This is covered by EU directives and regulations on the free movement of people. Originally, the Schengen agreements and the rules adopted between them worked independently of the European Union. However, in 1999, the Treaty of Amsterdam introduced them into EU law, while they provided exemptions for the only two EU Member States that had remained outside the territory: Ireland and the United Kingdom (which withdrew from the EU in 2020). Schengen is now a central element of EU law and all EU Member States that have not yet joined the Schengen area are legally obliged to do so if technical requirements are met. Several non-EU countries are included in this area.  In Germany, the ZV 34 department of the Bundeskriminalamt (BKA) indicates whether the data is actually stored in SIS II and which authority is responsible for correcting or erasing the data. If your personal data is stored in the second generation Schengen Information System (SIS II), you have the right to request access to this data and to ensure that it is entered correctly and legally or, if not, to require a correction or deletion. They can exercise this right in all states where SIS II is used, regardless of which Member State issues the tender. Ireland is not part of the Schengen area, which means that if you are travelling from Ireland within the Schengen area, you must pass through an immigration checkpoint and present your passport or ID card.