Final answer:
Firestore is a NoSQL database similar to AWS's DynamoDB, Microsoft Azure's Cosmos DB, and MongoDB. They are widely used by large-scale platforms needing high throughput and flexible data models, such as social media, analytics, and IoT.
Step-by-step explanation:
Firestore is an example of a NoSQL database, which is a type of database that provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Other companies offering products similar to Firestore include Amazon Web Services (AWS) with their service called DynamoDB, Microsoft Azure with Cosmos DB, and MongoDB Inc. with their flagship database service called MongoDB.
The major users of these NoSQL databases often include organizations with the need for large scale data storage that supports high throughput and flexible data models. These include social media platforms, real-time analytics, content management systems, mobile application development, and IoT applications.