Networking & Delivery
Ingress
Data flowing into a provider's network, which is typically free, in contrast to the egress it costs to send data out.
Ingress is data coming into a provider's network: uploads from users, data you push into cloud storage, traffic arriving at your servers. On almost every cloud it's free, which is a deliberate asymmetry. Providers happily accept your data at no charge because the cost lands later, when you read it back out as egress.
Understanding the split matters when you plan where data lives and moves. Uploading a terabyte to object storage costs nothing on ingress. Downloading it repeatedly is where the meter runs. This shapes real decisions, like keeping processing close to where the data already sits rather than shuttling it across networks.
In Kubernetes the same word means something different, the rules that route external traffic into the cluster, which is worth flagging so the two don't get confused. In the billing sense that concerns most people, ingress is simply the free direction.