There are three main group loot options in SWTOR: need, greed and disassemble (reverse engineering).
Need – You should choose need option if you can use the item and if it provides better stats than your current armor. Companions are important for every player, but the player’s character always have priority over any companion. Needing for a companion, without asking the group first, is usually an instant kick from the group.
Greed – You should choose greed option if you need an item for a companion, alt or a friend, or if you just want to sell it. The same rule stands for crafting materials, if you cannot use it choose greed option.
Disassemble (reverse engineering) – This option is available if a player in the group has required crew skill and if the skill level is high enough. If you win the roll, the item will be destroyed and you will get the crafting materials from the item.
You can also just click on the cross and close the group loot window, you will then pass on the roll.
I usually do this when i already have the item, or don’t need it but i know someone else in the group could use it, like when i’m on my Jedi and the item has cunning/endurance for example and there is a smuggler in the group.
Is disassemble the same as need? like does it give priority over greed.