An internet gateway (IGW) connects your VPC to the public internet. Without it, nothing in your VPC can reach external addresses.
Setup:
Create IGW and attach to VPC
Add route: pointing to IGW
Assign public IPs to resources needing internet
Characteristics:
- Horizontally scaled, highly available
- No bandwidth constraints
- No additional cost beyond data transfer
- One IGW per VPC maximum
Public IP requirement: Resources need a public IP or Elastic IP to communicate through the IGW. The IGW performs NAT between public and private addresses.