Clear, current definitions for the terms indie authors, coaches, and creators actually need to know. Each entry is concise enough for quick reference and thorough enough to settle a disagreement.
An ASIN (Amazon Standard Identification Number) is a 10-character code Amazon assigns to every product, including every Kindle ebook. It's Amazon-only and works as the product's unique identifier in Amazon's ecosystem. Unlike ISBN, you can't buy an ASIN or use it outside Amazon — it's generated automatically when you publish through KDP.
KDP Select is Amazon's optional enrollment program that grants Kindle Direct Publishing authors access to Kindle Unlimited page-read revenue, Kindle Countdown Deals, and Free Book Promotions in exchange for 90-day Amazon exclusivity on the digital edition.
KENP (Kindle Edition Normalized Pages) is Amazon's standardized page-count measurement for Kindle Unlimited. It normalizes every eBook to a common font, spacing, and margin model so KU per-page revenue is fair across the catalog. KENP is typically 1.0–1.3× your manuscript's page count.
A Kindle Countdown Deal (KCD) is a 7-day promotional pricing feature for books enrolled in KDP Select. During a KCD, authors can temporarily drop their book's price while keeping the 70% royalty rate (normally restricted to $2.99+). Available in US and UK only; limit one per 90-day Select period per book.
Kindle Unlimited (KU) is Amazon's subscription eBook service. Subscribers pay ~$12/month to read unlimited eligible books. Authors whose books are enrolled in KDP Select earn per-page-read revenue from Amazon's KDP Select Global Fund — typically $0.004–$0.005 per normalized page.
ACoS (Advertising Cost of Sale) is the percentage of ad-attributed sale revenue spent on advertising. Formula: (ad spend ÷ ad revenue) × 100. Lower ACoS means more efficient advertising. Most indie authors target ACoS under 40% for non-fiction, under 60% for fiction in Kindle Unlimited.
A lead magnet is a free piece of content (typically an 8–15 page eBook, cheat sheet, template, or video) offered in exchange for a prospect's email address. Lead magnets are the primary mechanism for turning anonymous website visitors into email subscribers who can later be nurtured into paying customers.
A tripwire offer is a low-priced product ($5–$25) offered immediately after a prospect opts in to a lead magnet. Its purpose isn't primarily revenue — it's to convert a freebie-seeker into a first-time buyer, because paying customers are 4–10× more likely to buy again at higher price points.
BISAC codes are standardized category codes that classify books by subject for publishers, bookstores, and retailers. Each code has a letter prefix (like FIC for fiction) and six digits identifying the subcategory. Choosing the right BISAC codes determines which Amazon categories your book can rank in — a high-leverage decision for self-publishers.
Book metadata is the structured information that describes your book to retailers — title, subtitle, author, description, keywords, categories, ISBN, price, series info, and more. It's how readers find your book via Amazon search, Google, and Apple Books discovery. Good metadata drives discoverability; bad metadata is why 95% of self-published books never get seen.
An ISBN (International Standard Book Number) is a unique 13-digit identifier assigned to every edition and format of a published book. Bookstores, libraries, and retailers use it to track a specific title across the supply chain. For ebook-only Amazon KDP, it's optional; for wide distribution, print, or libraries, it's essential.
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