You can launch an instance from an AMI using the AWS Management Console, AWS CLI, or SDKs.
Example (AWS CLI):
aws ec2 run-instances --image-id ami-0abcdef1234567890 --instance-type t2.micro --key-name MyKeyPair --security-groups my-sg
This command launches an instance using the AMI with the ID ami-0abcdef1234567890, of type t2.micro, with the specified key pair and security group.