zsh-ec2ssh lists up EC2 instances on your AWS account, and you can choose an instance graphically. Then zsh-ec2ssh issues a ssh command to login that instance. You often login EC2 instances if you are using AWS. Sometimes, you automate server generation, for example using autoscaling group; therefore, IP Addresses are not fixed. In that case, you need to look up the IP Addresses before ssh login. zsh-ec2ssh can make that work easier.