ISBN vs PID Explained: Do Books Need Both?

In the world of book publishing, tracking and identifying titles accurately is crucial for distribution, sales, and metadata management. Two terms that often appear in publishing discussions are ISBN and PID. While both serve as identifiers, they serve different purposes and are used in distinct contexts.

So, what exactly is the difference between an ISBN and a PID, and does your book need both?

Let us explore.

What is an ISBN?

ISBN stands for International Standard Book Number. It’s a globally recognized 13-digit identifier that uniquely distinguishes books and similar publications.

Key Facts About ISBN:

• Issued by official ISBN agencies in each country (e.g., ISBN Service in the US, Nielsen in the UK).
• Required for retail distribution, libraries, and booksellers.
• A different ISBN is needed for each format and edition of a book (e.g., paperback, hardcover, ebook).
• Helps track sales and catalog books in industry-standard systems like Books in Print.

Example:
A paperback version and a Kindle version of the same book should have two different ISBNs.

What is a PID?

PID stands for Product Identifier or Publisher Identifier depending on the context. It’s a more general or internal identifier used by some publishers or digital platforms.

Two Common Uses of PID:

1. Internal Product Tracking: Publishers or vendors assign a PID to track inventory or digital assets internally.
2. Platform-Specific Identification: Some distribution platforms (like Amazon KDP) assign their own unique identifiers (such as ASINs) that function similarly to PIDs.

Unlike ISBNs, PIDs are not standardized or recognized across the global publishing industry. They’re useful within a specific system or platform but do not provide the same level of visibility or legitimacy as ISBNs.

Key Differences Between ISBN and PID

Do Books Need Both ISBN and PID?

In Most Cases: Yes.

Here’s why:

• For Distribution and Sales:
  • If you plan to sell your book in online or physical bookstores, you need an ISBN.

  • Many retailers (Barnes & Noble, IngramSpark, Kobo, etc.) require ISBNs for listings.

• For Platform Management:
  • Platforms like Amazon assign their own identifier (e.g., ASIN), even if you provide an ISBN.
  • Your publisher might also assign a PID for internal reference or inventory management.

When Only a PID Might Be Enough:

• If you’re publishing exclusively through a closed platform like Amazon KDP, you can use their ASIN (a form of PID) without assigning an ISBN.
• If your book is an internal document, whitepaper, or private publication that won’t be sold to the public.

But if you want maximum reach, professionalism, and cataloging, an ISBN is essential.

When to Use an ISBN vs PID:

Amazon allows books to be published without an ISBN, but they will only be distributed through Amazon, not through broader retail or library networks.

Why Does This Matter to Authors and Publishers?

Understanding the distinction between ISBNs and PIDs is crucial for authors and publishers because it directly affects how books are distributed, tracked, and discovered. ISBNs play a vital role in ensuring your book is properly cataloged in global databases, making it accessible to retailers, libraries, and readers across different platforms. PIDs, while more limited in scope, help publishers and distribution platforms manage their own inventory and internal systems efficiently. By knowing when and how to use each identifier, you can maintain accurate metadata, prevent duplication, and make strategic choices about where and how your book is sold. For self-published authors, this knowledge also supports greater control over publishing rights, branding, and visibility in a crowded marketplace.

Final Thoughts: ISBN and PID Work Together, Not Against Each Other

ISBNs and PIDs serve different yet complementary roles in publishing. The ISBN acts as a universal identifier that enables global distribution and cataloging, while the PID helps with internal tracking or platform-specific management. Using both allows your book to be discoverable across sales channels and efficiently managed behind the scenes. Together, they ensure your publishing process is both professional and organized, one for the world to see, and one to keep things running smoothly.

As the publishing landscape continues to evolve, especially with the rise of digital platforms, it’s important to understand how different identifiers function. Relying solely on one system can limit your reach or cause confusion during distribution. By combining both ISBNs and PIDs appropriately, you position your book for greater success and easier management. It’s a small detail that can make a big difference in how your book is handled, discovered, and sold.

FAQs

1. Can I publish a book without an ISBN?

Yes, but only on certain platforms like Amazon. Without an ISBN, your book won’t be available in bookstores, libraries, or on many other platforms.

2. Is a PID the same as an ASIN?

A PID is a general term; ASIN is Amazon’s specific identifier for products, including books. ASINs are a type of PID.

3. Who assigns the PID?

Typically, the publisher or the platform (like Amazon, Apple Books, or Smashwords) assigns the PID for tracking purposes.

4. Does my ebook need a different ISBN from the print version?

Yes, your ebook needs a different ISBN. Each format (print, ePub, Kindle, PDF) should have a separate ISBN if it will be distributed widely.

5. Where do I get an ISBN?

ISBNs are purchased from the official ISBN agency in your country. In the US, that’s ISBn Services

Bottom Line:

• Use ISBNs for broad visibility, retail sales, and metadata integrity. Use PIDs for platform-specific or internal needs.
• One doesn’t replace the other, they serve different but complementary roles in the publishing ecosystem.