Vendor managed inventory (VMI) is a supply chain strategy where manufacturers are responsible for maintaining inventory levels at distributors. The manufacturer has access to the distributor's inventory data and generates purchase orders. VMI can reduce costs through lower inventories and smoother demand. Implementation requires agreement on replenishment and data exchange between suppliers and retailers. While VMI provided benefits for companies like Walmart and Procter & Gamble, obstacles to implementation include concerns about information sharing and operational changes required.