A running server instantiated from an AMI is referred to as an instance. All instances launched from the same AMI will create a nearly identical running server (except for the IP range or computer name).
The security group is analogous to a firewall that can block all incoming (ingress) and outgoing (egress) traffic that does not come in on a specific IP (specified by a CIDR) or port number range.
Amazon EBS volumes are off-instance storage that persists independently from the life of an instance.
You can create storage volumes from 1 GB to 1 TB that can be mounted as devices by Amazon EC2 instances.
EIP 是要給此機器一個固定的靜態 IP, 不過 IP 是給 Account, 並不是給任何一個 Instances.
Elastic IP addresses are static IP addresses designed for dynamic cloud computing.
Elastic IP addresses are associated with your account, not specific instances.