TencentDB for MongoDB involves the following concepts:

Instance: a standalone database environment running in Tencent Cloud. A TencentDB instance includes multiple databases created by users.

Replica set: a primary-secondary cluster supporting automatic failover and consisting of a primary node and one or more secondary nodes.

Sharded cluster: a sharded cluster consists of components such as shards, proxy sets, and config servers. Each shard contains a subset of sharded data. Each shard in TencentDB for MongoDB is deployed as a replica set.

VPC: a logically isolated custom virtual network space in Tencent Cloud.

Security group: security access control to TencentDB for MongoDB instances by specifying IP, protocol, and port rules for instance access.

Region and availability zone: physical location of a TencentDB for MongoDB instance and other resources.

Tencent Cloud console: web-based UIs.

Project: projects enable developers to better manage Tencent Cloud services based on the concept of projects by assigning different Tencent Cloud services to different projects.