Well, to truncate is to shorten by cutting off. In computer terms, when information is truncated, it is ended abruptly at a certain spot. For example, if a program truncates a field containing the value of pi (3.14159265...) at four decimal places, the field would show 3.1415 as an answer. This is different from rounding, which would result in the answer of 3.1416. I think that explains your question. Hope this helped!