Just targeting one mobile platform is not good enough anymore but building apps for lots of different mobile phone platforms could be a long and tedious task. Every smartphone platform has its own software development kit (SDK), these will need a developer to use different languages to be able to work with them all. You could easily end up with five or six code bases in order to reach a decent number of devices. So what to do if a mobile web site isn't seen as an acceptable alternative? Fortunately mobile apps and mobile web sites are two ends of a spectrum of possibilities. Sitting somewhere in the middle is PhoneGap Build, a service that lets you develop using Javascript, HTML and CSS and then builds apps for five platforms in the cloud.