EPUB and PDF eBooks
After you download an EPUB or PDF eBook from your library's digital collection to your computer, you can find the eBook's ACSM file in your computer's "Downloads" folder. The ACSM file is not the actual eBook; instead, it's a file that Adobe Digital Editions uses to download and open the eBook.
Once you open the eBook in Adobe Digital Editions, the actual EPUB or PDF file for the eBook will be stored in your computer's "[My] Digital Editions" folder (under "Documents").
Note that ACSM, EPUB, and PDF files from your library expire, meaning that they will only work for a limited time even after you download them to your computer.
Note: Kindle Books are currently available for US libraries only.
After you download a Kindle Book from Amazon's website to your computer, you can find the eBook's Amazon file in your computer's "Downloads" folder. You can transfer this file from your computer to a compatible Kindle eReader via USB.