What is a FOLIO File Type?
A folio is similar to InDesign because you can add .INDD documents, such as articles, a cover, a table of contents, to your folio. Folios can be created by InDesign CS5 and later.
The folio allows you to offer dynamic content to your readers with features such as small windows; displayed purchase on the top of the folio; a free article or a reset of the folio to a reader; s starting point. You can also create folios that adapt the content to the appropriate target device, such as an iPad or an iPhone.
You can create a folio, add articles to a folio, change properties of a folio, share folios, and even more using the Folio Builder. To open the Folio Builder select Window → Folio Builder.
Digital Publishing Service (DPS) allows you to share and publish folders using its DPS Folio Producer tool. If you are logged in with your checked Adobe ID, a workspace is automatically created on the acrobat.com web server when you create a folio.
After the 2014 release of DPS v32, InDesign CS5 and CS5.5 can no longer download folios to the DPS Folio Producer Service.