Zipline is Airbnb's machine learning data management framework. It handles feature engineering, discovering and accessing data sources, generating training sets, and monitoring data quality. Zipline includes a feature store, training set generation, and clients to access features and training data. It uses various data sources like Hive tables and streams data in and handles backfilling and mutations to training data. Zipline aims to make machine learning processes more scalable, robust, and transparent at Airbnb.