To free or not to free, that is the question every author must ask when releasing a new book. There are some very good things about setting your price to $0. For example:
It can give you access to a wider audience. This is especially helpful for new authors.
If you have a series of books, giving away the first for free could entice buyers to pay for the rest.
You can set your price to $0 as part of a limited time promotion to excite interest.
There are also some disadvantages to giving away your book for free:
No direct revenue (obviously)
Some consumers view free books as lower quality (if not part of a promotion)
Paid books tend to rank higher in the Kindle store than free books
You may be undercutting your value as an author due to low confidence
Finding the right place for "free" in your marketing toolkit is an essential exercise for every author. It can require a bit of trial and error to get the right mix, but if done right it can actually lead to higher sales. I currently have three short books available for free download:
To My Daughter, with Love
Soul Healing Solace: Affirmations to Renew Your Heart, Mind and Spirit
Becoming a True Man
My intention with this approach is to help readers get a sense for my writing style and content, become familiar with me as an author and seek out my other (not free) books.