Garlic routing is a variant of onion routing

Onion routing

Onion routing is a technique for anonymous communication over a computer network. Messages are repeatedly encrypted and then sent through several network nodes called onion routers. Like someone unpeeling an onion, each onion router removes a layer of encryption to uncover routing instructions, and...

 that encrypts multiple messages together to make it more difficult for attackers to perform traffic analysis.

Garlic routing is one of the key factors that distinguishes I2P

I2P

I2P is a mixed-license, free and open source project building an anonymous network .The network is a simple layer that applications can use to anonymously and securely send...

 from Tor

Tor (anonymity network)

Tor is a system intended to enable online anonymity. Tor client software routes Internet traffic through a worldwide volunteer network of servers in order to conceal a user's location or usage from someone conducting network surveillance or traffic analysis...

 and other privacy/encryption networks. The name comes from actual garlic

Garlic

Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

, whose structure this protocol resembles.

List of P2P applications that use garlic routing

• I2P
  I2P
  I2P is a mixed-license, free and open source project building an anonymous network .The network is a simple layer that applications can use to anonymously and securely send...
  
   - an anonymizing overlay network which allows applications to run on top of it (open source, written in Java)
• Perfect Dark
  Perfect Dark (P2P)
  is a Japanese peer-to-peer file-sharing application designed for use with Microsoft Windows . It was launched in 2006, its author is known by the pseudonym . Perfect Dark was developed with the intention for it to be the successor to both Winny and Share...
  
   - a P2P client which relies on a mixnet
  Mix network
  Digital mixes were invented by David Chaum in 1981. Digital mixes create hard-to-trace communications by using a chain of proxy servers. Each message is encrypted to each proxy using public key cryptography; the resulting encryption is layered like a Russian doll with the message as the...
  
   and distributed datastore
  Distributed file system
  Network file system may refer to:* A distributed file system, which is accessed over a computer network* Network File System , a specific brand of distributed file system...
  
   to provide anonymity (freeware, written for Windows
  Microsoft Windows
  Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
  
  )