Files with CSV (Comma Separated Values) extension represent plain text files that contain records of data with comma separated values. Each line in a CSV file is a new record from the set of records contained in the file. Such files are generated when data transfer is intended from one storage system to another. Since all applications can recognize records separated by comma, import of such data files to database is done very conveniently.
Files with .EPUB extension are an e-book file format that provide a standard digital publication format for publishers and consumers. The format has been so common by now that it is supported by many e-readers and software applications. For example, on Mac OS, the pre-installed Books software provides the support for opening such files. In addition, there are a lot of compatible software available for smartphones, tablets and computers.
You can also convert CSV into many other file formats. Please see the complete list below.