This post is originally meant for the Trading discussion, but I cannot post there for some reason.https://en.bitcoin.it/wiki/MtGox/API#Websocket_API
Ticker is published about every 30 sec. Depth is published every sec. Trade is only published sometimes.
In Ticker, buy means current highest price one can sell a bitcoin for USD. Sell means the current lowest price one can buy 1 Bitcoin for USD. Vol mean the number of Bitcoin in the market. I am not sure what high, low or vwap mean. (i.e what does 'close' mean in the description?)
In trade, amount means the number bitcoins that have been traded. Date is obvious. Item is the item that was traded, i.e Bitcoin. Price is how much USD it cost/Bitcoin. Currency is obvious. I'm not sure what bid means. Bid means that someone wanted to buy bitcoin for USD, whereas ask means someone wanted to sell Bitcoin for USD. If there is trade, shouldn't there be an ask for a bid and vice versa? Why is a trade labelled with either bid or ask and not both?
In depth, currency is obvious. Item is that is Bitcoin. Price for the Bitcoin. Ask means that someone wants to sell a Bitcoin. Volume is how much Bitcoin he wants to sell. Now is depth announced each time someone wants to bid or ask? What does negative number mean in the volume? What happens when someone doesn't want to bid or ask anymore, i.e. cancel? Depth is updated very frequently, with positive and negative numbers in volume for both ask and bid and often the same numbers appear multiple times. Shouldn't bids be only positive, while asks only negative?
Can you please explain it in detail what each field means? The description in the link is too short.