Describes the specified security groups or all of your security groups.

A security group is for use with instances either in the EC2-Classic platform or in a specific VPC. For more information, see Amazon EC2 security groups in the Amazon Elastic Compute Cloud User Guide and Security groups for your VPC in the Amazon Virtual Private Cloud User Guide.

We are retiring EC2-Classic. We recommend that you migrate from EC2-Classic to a VPC. For more information, see Migrate from EC2-Classic to a VPC in the Amazon Elastic Compute Cloud User Guide.