As the name suggests, EC2 Systems Manager is a management service that provides administrators and end users with the ability to perform a rich set of tasks on their EC2 instance fleet such as periodically patching the instances with a predefined set of baseline patches, tracking the instances' configurational state, and ensuring that the instance stays compliant with a state template, runs scripts and commands over your instance fleet with a single utility, and much, much more! The EC2 Systems Manager is also specifically designed to help administrators manage hybrid computing environments, all from the comfort and ease of the EC2 Systems Manager dashboard. This makes it super efficient and cost effective as it doesn't require a specialized set of software or third-party services, which cost a fortune, to manage your hybrid environments!

But how does AWS achieve all of this in the first place? Well, it all begins with the concept of managed instances. A managed instance is a special EC2 instance that is governed and managed by the EC2 Systems Manager service. Each managed instance contains a Systems Manager (SSM) agent that is responsible for communicating and configuring the instance state back to the Systems Manager utility. Windows Server 2003–2012 R2 AMIs, Windows Server 2003–2012 R2 AMIs will automatically have the SSM agent installed. For Linux instances, however, the SSM agent is not installed by default. Let's quickly look at how to install this agent and set up our first Dev instance in AWS as a managed instance.