What is an AMI?

An Amazon Machine Image (AMI) is a pre-configured template that contains the information required to launch an instance in AWS.

It includes:

• Operating system (e.g., Ubuntu, Amazon Linux)
• Application server (e.g., Nginx, Apache, Tomcat)
• Application code or configurations
• Custom software packages

An AMI acts as a blueprint for your EC2 instance.

When you launch an EC2 instance, you are essentially creating a virtual machine based on this AMI.

AMI Components

An AMI consists of:

1. Root Volume Template: Contains the OS and applications.
2. Launch Permissions: Controls who can use the AMI to launch instances.
3. Block Device Mapping: Defines which storage volumes to attach during launch.

Types of AMIs

1. AWS-Provided AMIs:

   Maintained by AWS. Examples: Amazon Linux, Ubuntu, Red Hat.

2. Marketplace AMIs:

   Provided by third parties via AWS Marketplace — for example, ready-to-use software stacks like WordPress or Jenkins.

3. Community AMIs:

   Shared publicly by AWS users for others to use.