Notes
A template is valid HTML with a <template> root tag.
<template>
....
</template>
When a component renders, the <template> tag is replaced with the name of the component, <namespace-component-name>.
For example, in the browser console, a component with the template myComponent.html renders as <c-my-component>, where c is the default namespace.
<template>
<c-my-component>
...
</c-my-component>
</template>