AWS CodeDeploy is a deployment service that automates application deployments to EC2 instances, on-premises servers, or Lambda functions. There are two deployment types: in-place, where the application is updated on each instance, and blue/green, where traffic is rerouted from the original environment to a replacement environment. Blue/green deployments minimize downtime and allow easy rollbacks. Getting started with CodeDeploy involves creating IAM roles, launching an EC2 instance, installing the CodeDeploy agent, preparing the application with an AppSpec file, and configuring CodeDeploy in the AWS console.