A namespace is used to group multiple resources together, and also avoid naming collisions: every created object needs to have a unique name - inside the namespace. Each Kubernetes cluster has a default namespace, but today we'll work in a specific namespace.
So let's start by creating a new namespace:
$ kubectl create namespace hands-on
Great! Now we have our new namespace. We can make sure it worked by listing all namespaces, with the kubectl get command:
$ kubectl get namespaces
Notice that you can use either kubectl get namespace or kubectl get namespaces, both will work. And if you are lazy, you can even use kubectl get ns, which is the shortname for namespace (you can see all supported shortnames in kubectl api-resources).
Now, we need to update our current context to run every command in this new namespace by default:
$ kubectl config set-context $(kubectl config current-context) --namespace=hands-on
This is the recommanded way to update your kubectl config (avoid manually editing the configuration file - use the kubectl config command instead).
So if you run the kubectl config get-contexts now, you will that our current context has a namespace set.
Note that even if by default, the hands-on namespace will be use, you can always force a specific namespace for a command, by using the --namespace flag.
At the end of the hands-on, if you want to delete everything, you can use the kubectl delete command to delete the namespace. But don't do it now! Otherwise you will have to re-create it again. Here is how you can delete the hands-on namespace, and all the resources created in it - But don't do it now!
$ kubectl delete namespace hands-on
So before deleting our namespace, let's put some resources in it, starting with some pods!