Deployments coordinate with ReplicaSets to manage pods. As we will see in this lesson, this enables high availability and auto-scaling.

It’s all about the state

Before going any further, it’s critical to understand three concepts that are fundamental to everything about Kubernetes:

• Desired state
• Current state (sometimes called actual state or observed state)
• Declarative model

Desired state is what you want. Current state is what you have. If the two match, everybody’s happy.

The declarative model is a way of telling Kubernetes what your desired state is, without having to get into the detail about how to implement it. You leave the how up to Kubernetes.