This document discusses using Redis as an online feature store and provides examples of companies that use Redis for this purpose. It highlights that Redis is well-suited for feature stores due to its ultra-low latency, support for multiple data structures, and high throughput. Major companies like DoorDash, AT&T, and Uber are highlighted as using Redis for online feature stores to power applications like fraud detection, recommendations, and personalization that have strict latency requirements. The document predicts increased adoption of online feature stores in 2022 and beyond to support real-time machine learning applications.