A .tox file is a Touch Component file, the file type used to save components of TouchDesigner projects. A .tox file contains one component which in turn can contain multiple components. The component file can then be loaded as needed in other projects. For example, when designing a custom user interface for a project, saving the UI elements as a separate .tox file would allow the parts of the user interface to be reused easily in future projects.
See also .toe.