Understanding .onion addresses and how onion services work
Onion services use the special .onion domain to let people browse and publish content anonymously through the Tor network. They provide more private ways to host websites, share files, communicate, and even access popular sites over secure Tor connections.
Onion services allow people to browse but also to publish anonymously, including publishing anonymous websites.
Onion services are also relied on for metadata-free chat and file sharing, safer interaction between journalists and their sources like with SecureDrop or OnionShare, safer software updates, and more secure ways to reach popular websites like Facebook.
These services use the special-use top level domain (TLD) .onion (instead of .com, .net, .org, etc.) and are only accessible through the Tor network.
When accessing a website that uses an onion service, Tor Browser will show at the URL bar an icon of an onion displaying the state of your connection: secure and using an onion service. To learn more about onion services, read How do Onion Services work?
A list of the Tor Project Onion Services is available at onion.torproject.org. Developers, researchers, and anyone curious about onion services can explore the Onion Services Ecosystem Documentation, which brings together content from many projects into a single searchable website for the wider Tor community.
Tor Browser's address bar showing an .onion address and the .onion security icon.