Mobile marketing involves communicating with customers through portable devices wherever they are. Projections estimate 6 billion iOS app downloads and 8 billion Android app downloads in 2012. Currently 52% of top US brands have mobile-friendly websites. When developing a mobile strategy, companies should consider where their users are located, what their users need, what devices their users have, and what existing content can be adapted. Apps have advantages like frequent use and access to device features, while mobile websites are better for search optimization and universal access. Measuring mobile marketing efforts includes tracking mobile interactions, conversions, and branding metrics.