File is a setting that affects the rendering output file. If selected, the file will save automatically in the chosen location. The file location is shown.

 

 

The Filename Prefix is the name of the rendering output file.

 

 

Choose Folder allows one to change the location of the rendering output file.

 

 

Unique Filename, if selected, the filename gets appended with a unique number so that multiple renderings will not override the same file.