When you are new to containers, and especially to Kubernetes, it is hard to figure things out immediately. However, to aid your understanding of the concept, take a look at the following diagram:

Deployments of containers to a Kubernetes cluster are defined in the so-called deployment file (1). In these deployment files, the desired state of the application is described. This desired state is described as a YAML file.

In this example, the desired state is a load balancer service and three pods (2). These pods are divided by the Kubernetes API on the nodes that run the containers (3). The service defined in the deployments file ensures that the traffic is routed to the specific pods. The deployment can be changed by updating it.

The scheduler can also change deployments when, for example, automatic scaling is configured for the application. In that kind of scenario, a fourth pod could be added to the cluster. In the service, there can also be an external load balancer to route traffic to the internal load balancer of Kubernetes (4).