File extension: .csv Developed by: Informational RFC Type of format: Multi-platform, serial data streams MIME: text/csv In computing, a comma-separated values (CSV) file stores tabular data (numbers and text) in plain text. Each line of the file is a data record. Each record consists of one or more fields, separated by commas. The use of the comma as a field separator is the source of the name for this file format.