Do you want to sell more books and increase the value of your author brand? Then give some of your e-books away for free.

To many authors, the idea of giving their work away for free is counterintuitive—and possibly abhorrent and sacrilegious. Free devalues your work, right?

Wrong. Free makes your work more valuable. As an author, you are a brand. Readers buy books from authors who have earned their trust. But to earn readers’ trust, you must first earn their awareness. If readers don’t know you, they can’t trust you—your brand carries no value to them. You’re invisible. Even if you’re already a New York Times bestseller, there are millions of potential readers out there who have never heard of you and have never read your stuff.

Free makes it possible to reach new readers who would otherwise never take a chance on you. Free enables readers to sample and discover new authors without financial risk.

According to the 2015 Smashwords Survey, free e-books get 41 times more downloads on average than other e-books. This is the power of free. Free drives sampling and discovery.

It’s like trying a free sample of cheese at the grocery store. You try it because it’s free and you like cheese. Once you taste something you love, you want more of it. Some percentage of the tasters become paying customers. Unlike with sample bites of food, readers must sample your entire book to appreciate the full flavor of your luscious literary genius. Partial samples are inadequate. Give them a free meal and then hook them with your awesome sauce.

Free works especially well for series starters. At Smashwords, we found that series in which the first book is free earn authors about 67% more income on average than other series.

One of the early indie pioneers of free series starters was Brian S. Pratt, a Smashwords author who writes epic fantasy. In 2009, he offered The Unsuspecting Mage, book one in his seven-book Morcyth Saga series, for free. The series starter is over 140,000 words, and by the time many of his readers finished it, they were hooked. Some loved Brian’s writing so much that they bought the next six books in the series, sight unseen, for $5.95 each. That’s trust. By offering his series starter for free, Brian made his writing more discoverable, more accessible, more desirable, and more valuable to readers.

Despite the proven power of free series starters, few traditional publishers take advantage of the idea. This means that, for the time being at least, the power of free is the sole domain of indie authors. Exploit this advantage while you have it.

Free is no guarantee of bestsellerdom. There’s a glut of high-quality free books. At Smashwords alone, we‘ve published more than 60,000 free books. The competition for reader eyeballs is fierce.

Free works best in the hands of a skilled writer. Your freebie must be a super-awesome book. Good is not good enough. A mediocre freebie will drive no more conversions to paid readers than a sample of rancid cheese will motivate a grocery store purchase. Longer freebies work better than shorter freebies because the longer the book, the more trust-building time the reader spends immersed in your writing.

Free can work well for standalone titles, too, because once you earn the reader’s awareness and love, they’ll seek out your other books. And, even if you’ll only ever publish one book, free can still work as a temporary promotional tool to ramp up readership, generate word of mouth, and establish your first retailer reviews.

All major e-book retailers allow free e-books. Amazon supports free but with caveats. If you’re in its KDP Select program, which requires exclusivity (boo, hiss!), you can only offer your e-book for free for up to five days per quarter. But this isn’t enough time to gain the full advantage of free.

To make free work, you want permafree, meaning that your book is free for weeks, months, or years. The best way to do this at Amazon is to opt out of KDP Select, distribute the book everywhere for free, and wait for the Amazon bots to price-match.

Free deserves a spot in your best-practices toolkit. Give it a try!

Mark Coker is the founder of Smashwords.