Mate is made from the leaves of a plant called yerba mate. The leaves are packed into the cup, hot water is poured in, and the drinker sips through the straw. Then more hot water is added, and the cup is passed to the next person. One cup goes around the whole circle of friends.
There is a quiet etiquette to mate. The host (called the 'cebador' - the pourer) keeps refilling the cup and passing it around. You drink your whole serving, then hand it back. Saying 'gracias' actually means 'I'm done for now', so don't say it until you're finished!
Argentine families drink mate first thing in the morning, with friends at the park, during long conversations, at work breaks. It is not a drink for one person in a rush - it is a way of slowing down and being together.
The leaves are bitter on their own, so the taste takes some getting used to. Many children drink it with a little sugar, or a slice of orange peel, or a leaf of fresh mint. Each family has its own way.