AWS RDS (Relational Database Service) pricing for Amazon RDS instances is based on several factors, including the database engine, instance type, storage, and data transfer. Here are the key components that contribute to AWS RDS pricing:

1. Database Engine: The pricing varies depending on the database engine you choose, such as Amazon Aurora, MySQL, PostgreSQL, Oracle, or SQL Server. Each engine may have its own pricing structure, and the costs can differ.

2. Instance Type: AWS offers a variety of instance types for RDS, each with different CPU, memory, and storage capabilities. The pricing varies based on the selected instance type and the amount of provisioned resources.

3. Multi-AZ Deployment: If you choose a Multi-AZ deployment for high availability and automatic failover, there may be additional costs associated with running a standby replica in a different Availability Zone.

4. Storage: AWS charges for the amount of storage used by your RDS database, including both the data and any automated backups. The pricing is based on the provisioned storage capacity in gigabytes (GB).

5. Provisioned IOPS: If your workload requires higher I/O performance, you can provision IOPS separately. Provisioned IOPS is an additional cost on top of the regular storage cost.

6. Data Transfer: AWS charges for data transferred in and out of your RDS database. This includes data transferred between your database and other AWS services within the same region, as well as data transferred between different regions.

7. Licensing: For certain database engines like SQL Server and Oracle, you need to consider the licensing costs in addition to the regular RDS pricing. You can bring your own license (BYOL) or choose to use the license-included option provided by AWS.