<p><a href="https://i.stack.imgur.com/iTlc3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iTlc3.png" alt="enter image description here"></a></p>

<p>What does the field mean?</p>

<p>Besides, if I will use it, what conditions my configuration need to meet?</p>

<p>A deployment creates pods. The template is a template for how to create those pods. If you want to use a deployment (where K8s automatically maintains a configured number of replicas of your pod) then you must have a template for creating the pods. Note that the spec part also belongs to the template.</p>

<p>See <a href="https://kubernetes.io/docs/concepts/workloads/controllers/deployment/" rel="nofollow noreferrer">the docs</a>.</p>
