Hi Anastasia, Congratulations on getting Kurzweil! It's a great program and I hope you'll enjoy it. The kes format is the native format of Kurzweil. The advantage of using it is that Kurzweil can open them really fast, so if you've scanned something and are reading or editing it, especially if it's long, you might want to use this format. But when it comes to Bookshare kes has 2 fairly major disadvantages. First, the files tend to be much larger than the same file in a different format, such as rtf or txt, would be. So uploading and downloading these files can take a long time, and might not be possible at all in some cases. The other disadvantage is that many people don't have Kurzweil, so if you submit kes files to Bookshare it may take a long time for them to be validated and join the collection. Rtf is a somewhat universal file format that maintains formatting like bold and italics, as well as page breaks and paragraph breaks. This is the preferred format to submit to Bookshare because almost everyone can access it and it keeps useful formatting. Txt is a very basic file format. It does not keep formatting such as page breaks in most cases, although there are various types of txt files which have different characteristics. One good thing about Kurzweil is that it makes txt files which do in fact maintain page and paragraph breaks. But since many word processors use the formatless type of txt it's better to submit rtf files unless there is a problem. Doc is the native format of MSWord. All the formats you mentioned in your message can be accepted by Bookshare. Hope this helps, and feel free to ask more questions about this if I missed something or you need more info. Kellie