An external link is a hyperlink to any page outside of Wikipedia or other Wikimedia sites. It is the opposite of a "wikilink", Wikipedia's term for internal links.

In most cases, external links belong in the "External links" (or ELs) section at the bottom of the page or in the Infobox. These provide entryway to information that doesn't belong in a Wikipedia entry. Official websites, interviews, and video resources are common examples.

Just to be clear: external links do not belong in the the body of an article. If you see an outbound link in an article's main text, you can change it!

Also, do not confuse "ELs" with citations or the "References" section, which often include outbound links, but are considered separately.

Three final points: go easy on the links; the guidelines say the fewer the better. Avoid linking to social media. And: not every article needs external links!