I2P is an anonymous network, exposing a simple layer that applications can use to anonymously and securely send messages to each other. The network itself is strictly message based (ala IP), but there is a library available to allow reliable streaming communication on top of it (ala TCP). All communication is end to end encrypted (in total there are four layers of encryption used when sending a message), and even the end points ("destinations") are cryptographic identifiers (essentially a pair of public keys).

What's New:

The 0.6.4 release adds performance and stability improvements.
Floodfill peers which are already connected, are preferred
for RouterInfo stores, and references to new floodfill peers
obtained from ordinary peers in case of shortage.

Preference for already connected peers is generally increased
by considering them active. Timeouts during tunnel joins
are now counted against peer profiles.

Improvements to the shutdown handler, tunnel builder,
router throttling, collection of tunnel pool statistics,
as well as router console and I2PSnark improvements
(and texts to explain reachability issues) are also included.

This release is backward compatible: if you already have
0.6.1.31 or greater installed, it will recognize the signature
on the signed update file, and you can update automatically.