Because most mobile applications are distributed for free or for a very low price, advertising is an essential ingredient in the business. Developers need to invest in marketing and advertising to create awareness of their apps, stimulate discovery and drive downloads. And they need to let other companies place ads within their apps to create a source of revenue. However, this advertising model can easily get out of synch if the app isn't compelling and the business is not carefully configured. How best should developers plan their ad-based strategies to attract advertisers, while also getting revenues from in-app purchases? Find out in this special feature.