Question - What Is A Collection?
Answer -
A series is a set of documents and their related JavaScript utility logic. A collection is a billable entity, in which the price is decided by way of the throughput and used garage. Collections can span one or greater partitions or servers and can scale to handle nearly unlimited volumes of storage or throughput.
Collections also are the billing entities for Azure Cosmos DB. Each collection is billed hourly, primarily based on the provisioned throughput and used garage area.