If you put a link to your website on your profile, and have your website link back to your profile, and put a "rel=me" attribute on your website's link...
...the link on your profile will get a check mark and turn a shiny green!
It's a great way to verify your identity (and you don't even need to be rich and famous to do it)!
(Fun tip: If you set your Mastodon profile as your profile link on Twitter, Twitter will add a "rel=me" attribute by default.)
A Mastodon instance specializing in Vocaloid, UTAU, and anything relevant to vocalsynth culture.