Amazon EC2 offers several pricing models: On-Demand, Reserved Instances, Spot Instances, and Savings Plans, Dedicated Hosts (Physical Server for Compliance), Dedicated Instances (Private Hardware)
Amazon EC2 instances are categorized into several types, including General Purpose, Compute Optimized, Memory Optimized, Accelerated Computing, and Storage Optimized, each optimized for different workloads.
Vertical scaling in EC2 refers to increasing or decreasing the resources (CPU, memory, network, etc.) of an existing instance by changing its instance type.
you can stop the instance the instance & then we can change the type of instance. we will have to start the instance. this is also known as vertical scaling.
If you've lost or misplaced the key pair for an AWS EC2 instance, you can regain access by Use Systems Manager Session Manager or Create a New Key Pair and Attach It .