Embedding other webpages - iframe, embed, object element

<iframe>s are for embedding other web pages,
Like disqus, yt video, or google maps

Attributes of `<iframe>`

sandbox Boolean Attributes requests heightened security settings
Always use sandbox Boolean Attributes
If absolutely required, you can add permissions back one by one (inside the sandbox="" attribute value) — see the sandbox reference entry for all the available options.
One important note is that you should never add both allow-scripts and allow-same-origin to your sandbox attribute — in that case, the embedded content could bypass the Same-origin policy that stops sites from executing scripts, and use JavaScript to turn off sandboxing altogether.

https://developer.mozilla.org/en-US/docs/Learn/HTML/Multimedia_and_embedding/Other_embedding_technologies#the_embed_and_object_elements
Note: In order to improve speed, it's a good idea to set the iframe's src attribute with JavaScript after the main content is done with loading. This makes your page usable sooner and decreases your official page load time (an important SEO metric.)