This tutorial on HashiCorp Learn teaches how to use application load balancers for blue-green and canary deployments, allowing developers to release new software with near-zero downtime. By using an AWS application load balancer (ALB) in combination with blue-green, canary, and rolling deployments, developers can incrementally promote a new application version via HashiCorp Terraform feature toggles. The tutorial also covers how to define ALB listeners and target groups to dynamically route traffic to services, enabling the running of canary tests and incremental deployment of new releases.