Similar to crew system in GTA Online, you can join up to 3 or 5 parties, but you can only have one active (the one that the server will take to show tags, party colour, MOTD and count for the party stats).
Sometimes it happens that you have your own party created (you like an specific colour for your name, or you like the tag you used, etc) but all your friends or people you want to play with are in other parties. This could make possible to be on their party too (changing to your active one) and have some good laughs in party chat while your own party is still created and you can move back when they left the server.
It will also make the party member limits go up and might get people to pay for a higher rank or the permanent rank to have 64 slots.
Sometimes it happens that you have your own party created (you like an specific colour for your name, or you like the tag you used, etc) but all your friends or people you want to play with are in other parties. This could make possible to be on their party too (changing to your active one) and have some good laughs in party chat while your own party is still created and you can move back when they left the server.
It will also make the party member limits go up and might get people to pay for a higher rank or the permanent rank to have 64 slots.
Congratulations to