<p>I've searched online and most links seem to mention manifests without actually explaining what they are. What are Manifests?</p>

<p>It's basically a Kubernetes "API object description". A config file can include one or more of these. (i.e. Deployment, ConfigMap, Secret, DaemonSet, etc)</p>

<p>As per <a href="https://kubernetes.io/docs/reference/glossary/?all=true#term-manifest" rel="noreferrer">this</a>:</p>

<blockquote>
  <p>Specification of a Kubernetes API object in JSON or YAML format.</p>
  
  <p>A manifest specifies the desired state of an object that Kubernetes will maintain when you apply the manifest. Each configuration file can contain multiple manifests.</p>
</blockquote>

<p>And a previous version of the documentation:</p>

<blockquote>
  <p>Configuration files - Written in YAML or JSON, these files describe the desired state of your application in terms of Kubernetes API objects. A file can include one or more API object descriptions (manifests).</p>
</blockquote>
