The movement of data between cloud services, regions, availability zones, or between the cloud and the internet. Egress (data leaving a cloud) typically incurs costs; ingress (data entering) is usually free. Understanding data transfer pricing is critical for cost optimization — cross-region transfers, CDN distribution, and Direct Connect/ExpressRoute can significantly impact cloud bills.
A media company stores video files in AWS S3 us-east-1 and serves them globally. By routing delivery through CloudFront (CDN), they reduce direct S3 egress costs by 60% and lower latency for viewers worldwide.