This document discusses how Walmart uses Apache Kafka to provide real-time inventory visibility across its large retail operations. As the world's largest retailer with over 5000 stores, 150 distribution centers, and 1000 vendors, Walmart needed a solution that could scale elastically to handle high volumes of inventory data and improve accuracy, speed, and reliability. Kafka was chosen to ingest up to 500 million events daily from 13 internal teams to power inventory management systems. Key learnings included optimizing Kafka Streams, connectors to Cassandra and HDFS, and ensuring reliability through design choices and operational practices.