Previously, repositories named username.github.com would become GitHub Pages.However, the new format for User and Organization Page repository names is username.github.io.

While both formats are supported, we highly recommend new repositories use the username.github.io format. If both a username.github.io and a username.github.com repository exist, the username.github.io version is used.

You do not need to rename old repositories from the .com name to the .io name, as GitHub Pages will continue to route the old repositories. However, keep in mind that a .com name will send you to a username.github.io website.