Ebook Metadata: The Hidden Key to Discoverability

Metadata is the structured information embedded in your ebook file that tells retailers, libraries, search engines, and accessibility tools what your book is about. Most indie authors spend hours perfecting their Amazon product listing while completely ignoring the metadata inside the EPUB itself, even though retailers use both, and in some cases the embedded metadata takes priority.

A 2025 analysis by the Book Industry Study Group found that ebooks with complete, optimized metadata received 34% more impressions in retailer search results compared to ebooks with only the minimum required fields. For accessibility metadata specifically, Amazon's internal quality systems now factor it into ranking decisions, meaning missing metadata can directly suppress your book's visibility.

This guide covers every metadata field that matters, explains exactly what each one does, and gives you copy-paste templates for common book types.

What Ebook Metadata Actually Is

When you open an EPUB file (which is just a ZIP archive), you will find a file called content.opf, the package document. This file contains three sections: metadata, manifest, and spine. The metadata section holds structured information about your book in XML format.

Here is a simplified example:

<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
  <dc:title>The Great Gatsby</dc:title>
  <dc:creator>F. Scott Fitzgerald</dc:creator>
  <dc:language>en</dc:language>
  <dc:identifier id="isbn">978-0-123456-78-9</dc:identifier>
  <dc:publisher>Scribner</dc:publisher>
  <dc:date>2025-01-15</dc:date>
  <dc:description>A novel about the American Dream...</dc:description>
  <meta property="schema:accessibilityFeature">tableOfContents</meta>
  <meta property="schema:accessibilityFeature">alternativeText</meta>
  <meta property="schema:accessibilityHazard">none</meta>
  <meta property="schema:accessibilitySummary">
    This ebook meets WCAG 2.1 AA accessibility standards.
  </meta>
</metadata>

E-readers, library systems, and retailer algorithms parse this XML to categorize, index, and evaluate your book. When a reader searches for a book on Kobo or Apple Books, the search engine queries metadata fields, not just the product listing you filled out on the retailer's website.

The Two Categories of Ebook Metadata

Bibliographic Metadata: What Your Book Is

These fields describe the fundamental identity of your book, title, author, language, subject. They are the metadata equivalent of what you would put on a library catalog card.

Accessibility Metadata: How Your Book Works

Accessibility metadata describes how your book can be consumed and what features it provides for readers with disabilities. Since mid-2025, this category has become commercially critical.

Why Metadata Matters for Sales

Retailer Search and Discovery

When a reader types "cozy mystery set in Vermont" into Amazon's search bar, the search algorithm evaluates multiple signals, your product listing keywords, your categories, your sales history, and your embedded metadata. The dc:subject and dc:description fields in your EPUB provide additional keyword signals that can influence search ranking.

Apple Books and Kobo place even more weight on embedded metadata because their ingestion pipelines extract information directly from the EPUB file during upload. If your dc:description in the EPUB is empty but your product listing has a rich description, Apple Books may display limited information in some contexts.

Library Discovery

Libraries use ONIX metadata records and EPUB metadata to catalog ebooks. OverDrive (which powers the Libby app used by over 90% of US public libraries) parses EPUB metadata during ingestion. Complete metadata improves your book's discoverability in library catalog searches, a channel that accounts for an estimated 8-12% of total ebook readership.

Accessibility Compliance and Ranking

Amazon's quality review system checks for accessibility metadata as part of its suppression risk assessment. Based on scans processed through Rahatt, missing accessibility metadata contributes 20 points to a book's suppression risk score (on a 0-100 scale). That alone can push a book from "Low Risk" to "Medium Risk" territory.

The European Accessibility Act, in effect since June 2025, requires ebooks sold in the EU to include accessibility metadata declaring the book's accessibility features. While enforcement in 2026 is still ramping up, retailers like Apple and Kobo have begun flagging books without accessibility metadata during the upload review process.

How to Optimize Each Metadata Field

Title (dc:title)

Your title in the metadata must exactly match your cover title. Do not add subtitles, series information, or keywords to the dc:title field, these belong in separate fields or in your retailer product listing.

Correct: <dc:title>The Midnight Garden</dc:title>

Incorrect: <dc:title>The Midnight Garden: A Cozy Mystery Novel (Rosewood Series Book 3)</dc:title>

If your book has a subtitle, use a separate title-type refinement:

<dc:title id="main-title">The Midnight Garden</dc:title>
<meta refines="#main-title" property="title-type">main</meta>
<dc:title id="subtitle">A Rosewood Mystery</dc:title>
<meta refines="#subtitle" property="title-type">subtitle</meta>

Author (dc:creator)

Use your publishing name exactly as you want it displayed. For pen names, use the pen name. For multiple authors, use separate dc:creator elements.

<dc:creator id="author1">Jane Smith</dc:creator>
<meta refines="#author1" property="role" scheme="marc:relators">aut</meta>
<dc:creator id="author2">John Doe</dc:creator>
<meta refines="#author2" property="role" scheme="marc:relators">aut</meta>

The role refinement uses MARC relator codes: aut for author, edt for editor, ill for illustrator, trl for translator.

Language (dc:language)

Use the correct ISO 639-1 two-letter code. This field affects screen reader pronunciation, hyphenation algorithms, and search filtering.

Common codes: en (English), fr (French), de (German), es (Spanish), pt (Portuguese), it (Italian), ja (Japanese), zh (Chinese), ko (Korean), ar (Arabic).

For regional variants, use the full BCP 47 tag: en-US, en-GB, pt-BR, zh-TW.

Description (dc:description)

Your EPUB's description should be a concise, informative summary, not marketing copy. Keep it under 500 characters. This field is used by library systems and some retailer search algorithms. Save your punchy sales copy for your retailer product listings.

Good: A description that summarizes the plot or topic, names the protagonist, and establishes the genre.

Bad: "YOU WON'T BE ABLE TO PUT THIS DOWN! The #1 bestselling thriller that has everyone talking!!!"

Subject (dc:subject)

Use standardized subject headings when possible. BISAC (Book Industry Standards Advisory Committee) codes are the standard for the US market. Thema codes are used internationally.

<dc:subject>FICTION / Mystery &amp; Detective / Cozy / General</dc:subject>
<dc:subject>FICTION / Small Town &amp; Rural</dc:subject>

You can include multiple dc:subject elements. These supplement (not replace) the category selections you make on retailer dashboards.

Accessibility Metadata: The Complete Setup

Here is a step-by-step guide to adding proper accessibility metadata to your EPUB. If you are using a tool that does not support adding these fields (most do not), you can edit the OPF file directly in Sigil, or use Rahatt's auto-fix feature which injects this metadata automatically.

Step 1: Declare Accessibility Features

Add one meta element for each accessibility feature your book provides:

<!-- Always include these if your book has them -->
<meta property="schema:accessibilityFeature">tableOfContents</meta>
<meta property="schema:accessibilityFeature">readingOrder</meta>
<meta property="schema:accessibilityFeature">structuralNavigation</meta>
<meta property="schema:accessibilityFeature">displayTransformability</meta>

<!-- Include if all images have alt text -->
<meta property="schema:accessibilityFeature">alternativeText</meta>

<!-- Include if your book uses page numbers mapped to print edition -->
<meta property="schema:accessibilityFeature">pageNavigation</meta>

displayTransformability means the content can reflow and the reader can adjust font size and colors. This applies to all reflowable EPUBs, include it unless your book is fixed-layout.

Step 2: Declare Hazards

If your book does not contain flashing content, motion simulation, or sound that plays automatically, declare none:

<meta property="schema:accessibilityHazard">none</meta>

If your book does contain hazards, list them specifically:

<meta property="schema:accessibilityHazard">flashing</meta>
<meta property="schema:accessibilityHazard">motionSimulation</meta>

Step 3: Declare Access Modes

Access modes describe how readers consume the content. Most text-based ebooks are textual. If your book includes images that convey information, add visual.

<meta property="schema:accessMode">textual</meta>
<meta property="schema:accessMode">visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>

The accessModeSufficient property declares that the book can be fully consumed through text alone (because images have alt text). If your book contains essential visual information without alt text, do not include this.

Step 4: Write an Accessibility Summary

This is a human-readable description of your book's accessibility features:

<meta property="schema:accessibilitySummary">
  This publication includes accessible structural navigation,
  a table of contents, and alternative text for all images.
  It is compatible with screen readers and supports text resizing.
</meta>

Keep it factual and specific. Only claim features that actually exist in your book.

Metadata Templates by Book Type

Fiction (Novel, No Images)

<meta property="schema:accessibilityFeature">tableOfContents</meta>
<meta property="schema:accessibilityFeature">readingOrder</meta>
<meta property="schema:accessibilityFeature">structuralNavigation</meta>
<meta property="schema:accessibilityFeature">displayTransformability</meta>
<meta property="schema:accessibilityHazard">none</meta>
<meta property="schema:accessMode">textual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
<meta property="schema:accessibilitySummary">
  This publication meets WCAG 2.1 Level AA. It includes a table of contents,
  logical reading order, and structural navigation. No images require
  alternative text. Content is fully accessible via text.
</meta>

Non-Fiction with Images

<meta property="schema:accessibilityFeature">tableOfContents</meta>
<meta property="schema:accessibilityFeature">readingOrder</meta>
<meta property="schema:accessibilityFeature">structuralNavigation</meta>
<meta property="schema:accessibilityFeature">alternativeText</meta>
<meta property="schema:accessibilityFeature">displayTransformability</meta>
<meta property="schema:accessibilityHazard">none</meta>
<meta property="schema:accessMode">textual</meta>
<meta property="schema:accessMode">visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
<meta property="schema:accessibilitySummary">
  This publication meets WCAG 2.1 Level AA. It includes a table of contents,
  alternative text for all images, logical reading order, and structural
  navigation. Visual content is described in text alternatives.
</meta>

Children's Picture Book (Fixed Layout)

<meta property="schema:accessibilityFeature">tableOfContents</meta>
<meta property="schema:accessibilityFeature">readingOrder</meta>
<meta property="schema:accessibilityFeature">alternativeText</meta>
<meta property="schema:accessibilityHazard">none</meta>
<meta property="schema:accessMode">textual</meta>
<meta property="schema:accessMode">visual</meta>
<meta property="schema:accessModeSufficient">textual,visual</meta>
<meta property="schema:accessibilitySummary">
  This fixed-layout publication includes alternative text for all illustrations.
  Text is embedded in fixed positions and cannot be resized.
  Content requires both text and visual access for full comprehension.
</meta>

Note the differences: fixed-layout books cannot claim displayTransformability, and accessModeSufficient requires both textual and visual when illustrations are integral to understanding.

How to Check Your Current Metadata

You do not need to unzip your EPUB to check metadata. Several tools can show you what is inside:

1. Rahatt, Upload your EPUB at rahatt.co and the scan results include a metadata assessment. Missing metadata is flagged as a suppression risk factor.
2. Calibre, Right-click your ebook, select "Edit metadata." Calibre shows basic metadata but not accessibility properties.
3. Sigil, Open the EPUB and navigate to the OPF file to see all metadata in its raw XML form.
4. EPUBCheck, The validation report lists metadata warnings and errors.

For the full validation workflow, see our EPUB validation guide.

Common Metadata Mistakes

Mistake 1: Empty or Missing dc:description

An estimated 40% of indie-published EPUBs have an empty dc:description field, according to a 2025 Smashwords metadata audit. This means library search systems and some retailer algorithms have no text summary to index. Always include a meaningful description.

Mistake 2: Wrong Language Code

Setting dc:language to English instead of en is a common error. EPUBCheck flags this, but many authors skip validation. The language code must be a valid ISO 639-1 or BCP 47 code. Incorrect language codes cause screen readers to use the wrong pronunciation engine, imagine your English novel being read aloud with French pronunciation rules.

Mistake 3: No Accessibility Metadata at All

The most impactful mistake. Over 80% of indie-published EPUBs scanned through Rahatt in 2025 had zero accessibility metadata. Adding the appropriate metadata from the templates above takes five minutes and can reduce your suppression risk score by 20 points.

Mistake 4: Claiming Features That Do Not Exist

Do not claim alternativeText as an accessibility feature if your images do not actually have alt text. Automated validation tools like DAISY Ace cross-check these claims against the actual content. A false claim is worse than no claim, it can trigger additional warnings.

Mistake 5: Using dc:date Incorrectly

The dc:date field should use ISO 8601 format: YYYY-MM-DD (e.g., 2026-03-15). Some tools insert dates in MM/DD/YYYY or other regional formats, which causes EPUBCheck errors and can confuse retailer ingestion systems.

Metadata and the European Accessibility Act

The European Accessibility Act (EAA) requires that ebooks sold in the EU include accessibility information so that consumers can make informed purchasing decisions. In practice, this means your EPUB needs accessibility metadata declaring what features it provides.

As of early 2026, enforcement varies by country. Italy and Germany have been the most active, with their national libraries flagging ebooks distributed through library channels that lack accessibility metadata. Amazon's EU storefronts have not yet begun rejecting uploads based on accessibility metadata alone, but they are factoring it into quality assessments.

The safest approach: add complete accessibility metadata to every ebook you publish. It takes minutes, costs nothing, and protects you from both current and future enforcement. For broader context on accessibility requirements, see our EPUB accessibility 101 guide.

Frequently Asked Questions

Does the metadata inside my EPUB override what I enter on Amazon KDP?

It depends on the field. Amazon uses your KDP dashboard entries for most customer-facing information (title, description, categories, keywords). However, the embedded metadata is used by Amazon's internal quality systems for validation, accessibility assessment, and suppression risk scoring. The dc:language field in the EPUB is also used for language detection. For best results, ensure your embedded metadata and KDP dashboard entries are consistent.

Can I add metadata without editing the EPUB manually?

Yes. Calibre's metadata editor handles basic fields (title, author, description, publisher, language) through a graphical interface. For accessibility metadata, Rahatt's auto-fix feature injects the appropriate properties automatically based on your book's content. Sigil also provides a metadata editor, but it requires more technical knowledge.

How many dc:subject keywords should I include?

There is no hard limit, but 5-10 well-chosen BISAC subject headings or relevant keywords is a reasonable range. These supplement the categories and keywords you select on retailer dashboards. Do not keyword-stuff, include only genuinely relevant subjects that accurately describe your book's content and genre.

Does metadata affect Apple Books ranking?

Yes. Apple Books places significant weight on embedded EPUB metadata for both search ranking and editorial curation. Apple's guidelines specifically recommend complete metadata including dc:description, dc:subject, dc:publisher, and accessibility properties. Books with complete metadata are more likely to appear in Apple Books editorial features and search results.

What happens if my metadata has errors?

EPUBCheck reports metadata errors and warnings. Common consequences: some retailers may reject the upload (Apple is strictest), library systems may catalog the book incorrectly, accessibility validation fails, and Amazon's quality score may be affected. Always validate your EPUB before uploading, our validation guide covers the complete process.