Domain fronting uses different domain names at different layers of communication
The censor sees one domain name, while the HTTP Host header contains another.
$ wget -q -O - https://www.google.com/ | grep -io '<title>.*</title>' <title>Google</title> $ wget -q -O - https://www.google.com/ --header 'Host: maps.google.com' | grep -io '<title>.*</title>' <title>Google Maps</title>
Works in many cases where multiple domain names are behind one frontend server: CDNs, Google, maybe others.
You can use domain fronting in order to reach a proxy running on a domain you control.