Old Prussian is an extinct Baltic language that was spoken by the Prussian people in the region that is now part of modern-day Poland and Lithuania. It belongs to the Baltic language family and is closely related to Lithuanian and Latvian. The language was primarily used until the 17th century, after which it gradually fell out of use due to the influence of German and Polish. The earliest written records of Old Prussian date back to the 16th century, with the most significant texts being religious in nature. Despite its extinction, Old Prussian is important for historical linguistics and provides insights into the culture and identity of the Prussian people. Efforts to study and revive interest in the language continue among linguists and historians.