The Import/Export tool gives you the ability to manage multiple customer and product records in a single operation. If you have a large catalog of products, you will find it much easier to export the data, edit the data in a spreadsheet, and then import the data back into your store.
The CSV file format separates each data element by a comma, and is used as the standard for data exchange operations. All spreadsheet and database applications support the CSV file format. If you are working with a Mac, you should save the data in the CSV (Windows) format.