Clans are special groups that team up and become popular by challenging other clans or having war against others. They are usually armored with enchanted diamonds and their weapons and tools are usually made of enchanted diamonds as well. Their bases are usually secretive and hard to find but clans are able to find them and raid them (if the people of the discovered base are enemies to the discoverers). They also welcome noobs or beginners to their base carefully and treat them with good trades and items such as elytra and diamonds and enchanted diamond armor and tools.
Some popular clans:
Picture of GHE base logo
GHE
OFA
BOD
TCE