AWS Auto Scaling is a service that helps you ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application. It automatically adjusts the capacity of AWS services to optimize performance and costs. Auto Scaling monitors your applications continuously and adjusts the capacity automatically to maintain steady, predictable performance at the lowest possible cost.

Auto Scaling can help you optimize how your application is used and reduce wastage and optimize cloud spend. It can increase and/or decrease the capacity of AWS services to optimize costs. Auto Scaling can be used with applications that rely on multiple AWS services that can scale. Scaling policies can be unified for multiple AWS services together. Both Amazon EC2 Auto Scaling and Application Auto Scaling services can be combined and included in AWS Auto Scaling.

Auto Scaling groups are a group of Amazon EC2 instances that Auto Scaling manages. While creating an Auto Scaling group, you must first specify either the launch configuration or the Launch template you created. You must also specify how many running instances you want Auto Scaling to provision and maintain using the launch configuration or template you have created.

In summary, AWS Auto Scaling is a service that automatically adjusts the capacity of AWS services for application performance. It helps you maintain optimal application performance and availability, even when workloads are periodic, unpredictable, or continuously changing. Auto Scaling can be used with applications that rely on multiple AWS services that can scale. Auto Scaling groups are a group of Amazon EC2 instances that Auto Scaling manages.