AWS is a cloud computing platform that provides on-demand computing resources and services. The key components of AWS include Route 53 (DNS), S3 (storage), EC2 (computing), EBS (storage volumes), and CloudWatch (monitoring). S3 provides scalable object storage, while EC2 allows users to launch virtual servers called instances. An AMI is a template used to launch EC2 instances that defines the OS, apps, and server configuration. Security best practices for EC2 include using IAM for access control and only opening required ports using security groups.