When you buy an ebook, you may see DRM, “DRM-free”, Adobe DRM or .acsm. They sound technical, but answer a simple question: which devices can open this file, and with which account.
They do not, on their own, say what you may legally do with a book. The licence matters too. Keeping format, protection and permission separate avoids most surprises when moving an ebook to a Kindle, Kobo or new reading app.
DRM: protection that limits where an ebook opens
DRM means Digital Rights Management. It is technical protection that controls access to or copying of a digital file.
When you buy an ebook with DRM, you do not usually receive a file you can open on every reader. You receive the right to read it in the apps and devices authorised by the shop, using the account that bought it.
For example, Kindle ebooks with DRM are meant for Kindle devices and apps. Kobo uses Adobe DRM for some books; those are authorised and transferred through Adobe Digital Editions. DRM is not a fault in the file: it is a choice made by the publisher or retailer.
DRM-free: more portable, not free of copyright
A DRM-free ebook has no such technical lock. If you receive the EPUB or PDF file, you can keep it and open it on compatible readers. Amazon lets verified purchasers download EPUB and PDF files for titles a publisher has explicitly marked DRM-free. Amazon explains the DRM/DRM-free distinction.
That makes a file easier to take from one device to another, but it does not make it public domain or a file you may give away or publish. “DRM-free” answers how the file is protected; the licence answers what uses it permits.
EPUB, PDF and DRM are different things
They are easy to confuse because they appear together when you download a book:
- EPUB and PDF are formats. They describe how content is arranged: reflowable text in EPUB, a fixed page in PDF. We explain the difference in EPUB or PDF: what’s the difference?.
- DRM is technical protection that can sit inside either an EPUB or a PDF.
- A licence is permission from the publisher, shop or author. It can limit a DRM-free file to personal use.
An EPUB can carry DRM, a PDF can carry DRM, and a DRM-free EPUB can still be a commercial book protected by copyright.
What is an .acsm file?
A file ending in .acsm is not the book. It is a small Adobe licence file that downloads and authorises the protected ebook. You open it in Adobe Digital Editions, which then gets the associated EPUB or PDF for the authorised account.
That is why you cannot copy an .acsm onto a Kobo or open it as an EPUB. You first need to complete Adobe Digital Editions' authorisation process. Kobo explains that EPUB and PDF files with the ACSM extension are DRM-protected, and that Adobe Digital Editions is needed for Adobe DRM. See Kobo's supported formats.
What works in each case
| What you have | What usually works |
|---|---|
| A DRM-free EPUB or PDF you have the right to use | Read it on a compatible device; copy it to a Kobo; send an EPUB to Kindle with Send to Kindle |
| A DRM-protected Kindle ebook | Read it with your account in Kindle devices or apps |
| An EPUB/PDF with Adobe DRM | Authorise it with Adobe Digital Editions and transfer it to a compatible reader such as Kobo |
An .acsm file |
Open it in Adobe Digital Editions; it is not an ebook you can read by itself |
The retailer's and publisher's terms always apply. Do not remove DRM or look for tools to do so: besides potentially breaking the licence, you can lose updates, sync and access to the book.
What it means for Pecia
Pecia can track a book wherever it lives: Kindle, Kobo, paper or another app. Pecia Sync will read data such as the title and reading progress from a connected reader; it does not copy or decrypt ebooks it finds.
Pecia Vault will accept only DRM-free EPUB and PDF files that you choose to add. A DRM-protected book or .acsm file is rejected before upload. And a DRM-free file remains private: DRM-free does not mean it may be lent or shared.
If you have an unprotected text PDF that you want to read better on an e-reader, try Pecia's PDF to EPUB converter. Changing the format does not remove DRM or change a licence; it just helps the text fit the screen.