That plugin, developed by WordPress co-creator Matt Mullenweg, is one of only two plugins that comes included with every WordPress installation. The other one is Akismet. If you activate the plugin, it will display a line from the lyrics for the Hello Dolly song in the top right corner of your administration panel.
The song was originally performed by Carol Channing as part of the Hello Dolly Broadway musical, but the most famous version is Louis Armstrongs cover. Hello Dolly was the most successful single of his career. It reached the number one spot on the Billboard Hot 100 and was inducted in the Grammy Hall of Fame in 2001.
The Hello Dolly plugin has been included in WordPress since version 1.2 of the system, which first introduced the plugin structure. Hello Dolly was meant to be a simple example of how plugins work in WordPress. Over time, it has become one of the most iconic parts of the WordPress administration panel. To me, it’s a reminder of the humble beginnings of what today is the biggest content management system on the web. That’s why it’s included in the footer of this website.
Still, the Hello Dolly plugin doesn’t serve much of a practical purpose. If you want to clean up your plugin list, feel free to deactivate and delete it. Or you can replace it with a plugin that displays quotes from Star Wars.