Outbound link
An outbound link is a link on your page that points to a different website.
Outbound links (sometimes called external links) are how you reference, cite, or recommend other sites. They are the mirror image of an inbound link: your outbound link is the destination site's inbound link. Linking out to credible, relevant sources is a normal part of good content and can help search engines understand your page's topic and neighborhood.
Outbound links do pass link equity away from your page, but this is not something to fear. Google has been clear that linking to authoritative sources is healthy, and a page with zero outbound links can look unnatural. Use rel sponsored on paid or affiliate links and rel ugc on user-generated links to stay compliant with Google's guidelines.
The honest caveat: be selective about where you link. Repeatedly linking out to spammy, low-quality, or unrelated sites (especially with exact-match commercial anchors) can associate your page with a bad neighborhood and, in extreme cases, contribute to a link spam signal. Link out as you would cite a source you trust.