What year was preschool invented?

There's no single year that marks the "invention" of preschool. The concept of early childhood education developed gradually over time. While kindergartens emerged in the mid-19th century (with Friedrich Fröbel often credited with its formalization), the types of programs we recognize today as preschool evolved over many decades, influenced by various educational philosophies and societal needs. There's no single inventor or date of origin.