Censorship on the clearnet operates through several mechanisms: DNS filtering blocks domain resolution, IP blocking prevents connections to known server addresses, and BGP hijacking redirects traffic at the network level. Tor 隱藏服務 are immune to all three. They use no DNS - .onion addresses are resolved within the Tor 網絡. They have no public IP 位址. And Tor's encrypted, multi-hop routing prevents network-level interception.
Even in countries that attempt to block Tor itself, the network provides 橋接 中繼 and pluggable transports that disguise Tor traffic as ordinary HTTPS, making it extremely difficult to block without shutting down the entire internet. Readers in 中國, 伊朗, 俄羅斯, and other censoring nations can access your .onion site using Tor with 橋接.
The .onion addressing system itself is 抗審查. No registrar can seize your address, no ICANN policy can revoke it, and no court order can redirect it. Your .onion address is derived from your cryptographic key, and as long as you control that key, you control the address. This is a fundamental architectural advantage over clearnet 主機代管.