This document discusses how context influences mobile content strategy and user experience. It uses the example of two train systems, BART and Caltrain, to illustrate how travel duration, environment, and device usage vary between the two. Shorter BART rides favor quick mobile browsing on phones, while longer Caltrain commutes allow for tablet-based longform reading. The key contexts of time, environment, and user experience place constraints on content and product design. An effective mobile strategy considers these relevant constraints to cater the platform, design, and features to the usage context.