[cm2187]

And if you just double click on a csv file to open it in excel (rather than importing from excel), excel will happily corrupt your data. Trim leading zeros in IDs, round large integers, not spot the date column is in us vs european format, etc.

[uncharted9]

Excel will happily ignore if you use tabs as delimiter and show all the columns as a single column. Atleast LibreOffice tries to figure out and confirms the delimiter before opening CSV.