What does the extension .twbx represent in Tableau?

A .twbx is a packaged workbook — a zip archive containing the .twb workbook file along with a copy of the data extract and any local resources such as background images or custom shapes.

The point of it is portability. Because the data travels inside the file, it opens on a machine that has no access to the original source, and it is what Tableau Reader can read.

The trade-offs are size and freshness: the file is much larger than a .twb, and the figures are frozen at the moment it was saved.

There is also a governance consideration worth raising — sending a .twbx hands the underlying rows to the recipient, which is not always what the sender intends.