A CSV (Comma-Separated-Variable) file is a data file where the fields are separated by a comma. In many cases the first row of the file contains the field or column headings, as shown below:

Below is a link to the sample CSV file shown above:

http://www.exchangewise.net/Downloads/Documents/OutlookWise/Outlook_Contacts.csv

By default if you open a CSV file and you have Microsoft Excel installed, the file should open in Excel, as shown below: