http://e55lzoju6enqswtvm66sk3uqukcin3377ehgiorplj4d7qyssipls4yd.onion/en/why-unijoin.php
CoinJoin is a method where different people join together a single pool and together create a single transaction where each of them give coins as inputs and fresh & anonymous addresses as outputs. The goal is to break the link between input & output, so that no one can retrieve from which input the output comes.