The oEmbed standard is a wonderful development if you’ve ever had to struggle with taking clunky
<script> tags or
<iframe> embeds and add them to a piece of content. Essentially, the technology makes it possible for a consumer (that’s you!) to add a request, usually in the form of a link, to the provider (such as YouTube or Twitter) so that a piece of rich media can be displayed within a webpage. In layman’s terms, it means that to embed a YouTube video on a WordPress site, all you have to do is add a link to the post, and voila! You have Rick Astley, making sure you know he’s never gonna give you up.
In WordPress, this standard has been implemented in a pretty slick fashion. Not only does WordPress do all the heavy lifting for you in recognizing when a request is to a known oEmbed provider (you can check out the list of “whitelisted” providers that WordPress supports in the Codex), but the UX for actually adding an oEmbed to a post is fantastic.