From LQWiki

CSV stands for comma separated value and is more-or-less standard way of storing data in a file. As such it used widely for dumping data from applications for export/import between different applications.

example:

 ID1, "FirstName1 LastName1", "Address containing spaces1", 10123456789
 ID2, "FirstName2 LastName2", "Address containing spaces, comma's etc.", 20123456789

See also: Wikipedia about csv