I've looked at various websocket feeds from crpyto exchanges and they in general are like this

{
  "jsonrpc": "2.0",
  "method": "ticker",
  "params": {
    "ask": "0.054464",
    "bid": "0.054463",
    "last": "0.054463",
    "open": "0.057133",
    "low": "0.053615",
    "high": "0.057559",
    "volume": "33068.346",
    "volumeQuote": "1832.687530809",
    "timestamp": "2017-10-19T15:45:44.941Z",
    "symbol": "ETHBTC"
  }
}

As i understand a ticket is a feed on every price change.. so sure enough the wss feed streams updates for the coin pair as the price changes.

What is not clear is what do the open, high, low, last fields represent ? The open of what ? Since the previous price change just milliseconds ago ?

Can someone explain wither from a polled REST feed or streamed websocket feed what these numbers are really referring to please given the gap bet between received data is so short ?