<slot>
A placeholder inside shadow DOM that light-DOM children fill.
Baseline: Widely available · Scripting
When to use it
In web components: named slots receive elements with matching slot attributes; default slot takes the rest.
When not to
Meaningless outside a shadow tree — it's web-component plumbing, not page content.
Key attributes
name- the slot's name
Example
<template shadowrootmode='open'>
<header><slot name='title'>Untitled</slot></header>
<slot></slot>
</template>