A Deployment provides declarative updates for Pods and ReplicaSets.

The following are typical use cases for Deployments:

• Create a Deployment to rollout a ReplicaSet. The ReplicaSet creates Pods in the background. Check the status of the rollout to see if it succeeds or not.
• Declare the new state of the Pods by updating the PodTemplateSpec of the Deployment. A new ReplicaSet is created and the Deployment manages moving the Pods from the old ReplicaSet to the new one at a controlled rate. Each new ReplicaSet updates the revision of the Deployment.
• Rollback to an earlier Deployment revision if the current state of the Deployment is not stable. Each rollback updates the revision of the Deployment.
• Scale up the Deployment to facilitate more load.
• Pause the Deployment to apply multiple fixes to its PodTemplateSpec and then resume it to start a new rollout.
• Use the status of the Deployment as an indicator that a rollout has stuck.
• Clean up older ReplicaSets that you don't need anymore.

reference: link

The following is an example of a Deployment. It creates a kubernetes configuration to bring up nginx Pods and Service:

levis:
  name: "nginx"
  deployment:
    containers:
      image: "nginx"
  service:
    enable: true

this example: [link] (https://github.com/kubeopsskills/levis/blob/develop/examples/levis.yaml)