The CSV file format is commonly used in spreadsheets, and it's pretty well known to programmers as one of the easiest formats to read and write data with. Why? Take a look at what a CSV file's contents could be:
2345, 345, sdfgsd, 3453,If you look past the stupidity of the bogus "data" I used in that example, you'll see that it's fairly simplistic! Every value is separated by a comma - hence, Comma Separated Values (CSV).
wgdg, 34, fsg, dgd, 34534.634,
sfsfggsdfgsdfgsdfh, 4, "hello",
Before I show you how to use CSV, you should know that I made an "Introduction to D3" tutorial earlier. I highly recommend that you read it first.