Are Closed Prices just the last trade or are they averaged? Since these exchanges run 24/7, are the posted close prices (say if the chart shows 1 hour increments like on bitcoinwisdom.com) based on the last trade for that time frame?  Or are they averaged over that time frame?
They are the endpoints. You can easily see that because in a bar chart, the bars always align with either the top or the bottom of the previous bar.