What is the difference between Milvus collections, partitions, and shards?

A collection is the top-level container for related data, similar to a table, with a defined schema and index configuration. Partitions are user-defined logical groupings inside a collection, used to organize data so queries can target specific subsets like per-date or per-tenant without full-collection scans. Shards are physical divisions of a collection distributed across worker nodes for parallel query processing, with a fixed count set at creation. Partitions are for logical organization and query filtering, shards are for physical scaling.