Podcasts officially began about 20 years ago, and at their inception, it would have been tough to predict their significant benefit to book marketing programs. Today, they are a strong and credible rival to radio interviews, and authors can become podcasters with very little expense and relatively little time. Like blogs, podcasts attract specialized audiences with high interest in a topic. When it matches your book, the benefits are self-evident. Book buyers/target readers will be the people with the most interest. It's why niche marketing continues to gain steam; it's efficient and gets excellent results.

What's so good about podcasts? The first important advantage is their long-form format. More time means you can dig deeper into the topics you're discussing and provide more depth. People who understand more become more interested and gravitate toward you and your book. It's also possible to build rapport with a listener when you have time and aren't talking in sound bites. If applicable, you can work on your key messages gently and discuss them from more than one angle. People can listen on demand at the time of their choosing. It helps you build a larger audience and sell books steadily.

Interviews and conversations on podcasts are more freewheeling and authentic. Audiences notice and appreciate the openness, which enhances the rapport-building potential. Often, podcasts on complex topics occur in a series and can discuss in parts similar to the chapters of a book. They also achieve intimacy and allow you to build relationships with the listeners. Many authors offer their podcasts free as a book promotion tool, but some charge to listen, and they may be part of a larger package of information. Self-help gurus and others in the teaching business see the value in podcasting. 

Again like blog posts, podcasts live forever online. It means you may sell books and be offered other opportunities years after a post. It's very different from traditional media years ago when there was a single air date for an interview, and it disappeared afterward. You can also launch your own podcast series and appear as a guest in other podcasts to extend your reach. Like radio interviews, they work well by phone when you can't be present in person. In the same vein, people can listen to podcasts anywhere in the world, and it greatly expands your audience – all at an affordable start-up cost.