CSV Import / Export is a Sitefinity solution, that allows you to import and export CSV. Just upload the CSV, map the fields, choose how to resolve the conflicts and import. We did the CSV import / export tool as we quickly realized that almost any software product on the planet offers some way of CSV import / export. If not directly through the UI, then maybe through it's database.
From legacy accounting software, through websites, most systems / websites have the ability to export content to either CSV or Excel (which in most cases can again be easily converted to CSV).
Most database management tools also allow you to export your query results to CSV or Excel file. This means that you can easily import data from arbitrary system to Sitefinity.
We also added support for images, documents and videos export. So you can now for example export users with avatars (it exports to zip in this case) and have them imported on another Sitefinity instance seamlessly. Same for any other content that has images or documents (like dynamic modules for example).