I just got a historical price data of cryptocurrencies from a R package called crypto, it says the data is scraped from coinmarketcap.com. I am planning to do some research based on this data, but I have some difficulties understanding some of its columns.

The data contains open, high, low, close price for each day. It also has 4 columns that I do not understand, which are volume, market, close_ratio, and spread.

I am not sure if the volume is in dollars or in shares. I am not sure what market means, is it market cap? Is it in dollars or shares?

The spread seems to be the difference between daily high and low price, but this only applies to very few observations. Is this data flawed, or the calculation of spread is more complicated than I thought?

I am new to this forum and I am not sure how to upload a picture here, so I will type the data value of bitcoin on 2018-09-06. It says the close price is 6529.1, volume is 5523470000, market is 116535117253, close_ratio is 0.3551, and spread is 350.42.