These are two scenarios that represent the concept of elasticity on AWS. Elasticity means the ability to adjust the resources and capacity of the system in response to changes in demand or environment. Scaling the number of Amazon EC2 instances based on traffic means using services such as AWS Auto Scaling or Elastic Load Balancing to add or remove instances as the traffic increases or decreases. Resizing Amazon RDS instances as business needs change means using the Amazon RDS console or API to modify the instance type, storage type, or storage size of the database as the workload grows or shrinks. You can learn more about the concept of elasticity on AWS from [this webpage] or [this digital course].