There are several ways to loot an item from an enemy. The first one is by killing it. They will also yield an item if a Theif steals from it. If a Bard happens to have the Lorekeeper level 5 talent, then it will have a chance to drop two items. When playing with multiple people they will want to distribute the items fairly, and to do that they will use the command -roll to determine who gets the item. Refer here for more information about game etiquette.
Several different item types may drop from an enemy. They can drop equipment, recipes, crafting materials, consumables, mana crystals, and gold. Gold is dropped by all enemies and is given to all players around the killed enemy. Mana crystals may also be given to all players killed around certain enemies.