Hello. Welcome to Module 2. In this module we would learn the main EC2 concepts and launch an EC2 instance. Let's take a look at the life cycle.
Every EC2 instance would go through the launch, then it will be pending, and then it will go into the running status. From the running status you can either stop it, but only if it's an EBS backed instance. And EBS stands for Elastic Block Store. Or you can reboot it, and then obviously any instance could be terminated.
Termination means a complete removal from the cloud, from your system, from your infrastructure, while start and stop, it's resumable, it's basically, you can start and stop instances many times. But once it's terminated, that's it. You cannot start it over again.
And each instance created from an image, it's called Amazon Machine Image, AMI. Let's talk about "Stopped" to "running" status. Every time you stop an instance, you would be billed for an additional hour. So basically, even if you run that instance for just five minutes, you will be billed as if it were an hour. If you start and stop an instance five times within an hour, you would be billed, guess how many times. No, not just an hour, but five hours.
Then, every time you run an instance you started, you would be getting a new private IPv4 address, unless you're inside of a VPC. If you're inside of a VPC, the private addresses would remain the same if you start and stopping an instance. And then also, if you enable the public IP address for that instance, you would get a new public IP every time you start and stop.
And as I mentioned before, only Elastic Block Store instances could be stopped and then started over. You can follow this link for more differences between reboot, stop, and terminate, and more details on stopped versus running.