This paper provides a literature review on the design and control of manual order-picking processes in warehouses. Order picking is the most labor-intensive and costly activity in warehouses, accounting for up to 55% of total warehouse operating expenses. Efficient order-picking processes require robust design and optimal control. The paper reviews recent research on key decision problems in order-picking design and control, including optimal layout design, storage assignment, routing, order batching, and zoning. It highlights the growing complexity of order-picking systems due to trends in manufacturing and distribution, such as smaller lot sizes, order customization, and tighter delivery windows. The paper also discusses the importance of integrating value-adding activities into the order-picking process and the role of warehouses in product recovery and redistribution. It reviews various order-picking systems, including manual and automated systems, and discusses their characteristics, advantages, and challenges. The paper also addresses key objectives of order-picking systems, such as maximizing service levels, minimizing travel time, and optimizing resource usage. It reviews recent research on layout design, storage assignment, and zoning, and discusses the trade-offs between different storage policies. The paper concludes that while there is a growing body of research on order-picking systems, there is still a gap between academic research and practical applications, and further research is needed to address the challenges of integrating order-picking with other warehouse operations.This paper provides a literature review on the design and control of manual order-picking processes in warehouses. Order picking is the most labor-intensive and costly activity in warehouses, accounting for up to 55% of total warehouse operating expenses. Efficient order-picking processes require robust design and optimal control. The paper reviews recent research on key decision problems in order-picking design and control, including optimal layout design, storage assignment, routing, order batching, and zoning. It highlights the growing complexity of order-picking systems due to trends in manufacturing and distribution, such as smaller lot sizes, order customization, and tighter delivery windows. The paper also discusses the importance of integrating value-adding activities into the order-picking process and the role of warehouses in product recovery and redistribution. It reviews various order-picking systems, including manual and automated systems, and discusses their characteristics, advantages, and challenges. The paper also addresses key objectives of order-picking systems, such as maximizing service levels, minimizing travel time, and optimizing resource usage. It reviews recent research on layout design, storage assignment, and zoning, and discusses the trade-offs between different storage policies. The paper concludes that while there is a growing body of research on order-picking systems, there is still a gap between academic research and practical applications, and further research is needed to address the challenges of integrating order-picking with other warehouse operations.