Sometimes we don't know in advance what kind of DOM element to render. <svelte:element> comes in handy here. Instead of a sequence of if blocks...

{#if selected === 'h1'}
  <h1>I'm a h1 tag</h1>
{:else if selected === 'h3'}
  <h3>I'm a h3 tag</h3>
{:else if selected === 'p'}
  <p>I'm a p tag</p>
{/if}

...we can have a single dynamic component:

<svelte:element this={selected}>I'm a {selected} tag</svelte:element>

The this value can be any string, or a falsy value — if it's falsy, no element is rendered.