An Internet Gateway (IGW) is an AWS networking component that allows communication between a Virtual Private Cloud (VPC) and the internet. It enables resources in a public subnet to send and receive internet traffic.
With an Internet Gateway, resources such as Amazon EC2 instances with public IP addresses can access the internet, and users on the internet can access public applications hosted in AWS.
In simple words, an Internet Gateway connects your AWS VPC to the internet, allowing public resources to communicate with the outside world.