We argue that the feature interaction problem arises primarily from sharing of context and hence features should be structured and analysed through a notation that makes context explicit. We support this argument with three sets of evidence. Firstly, we express feature interaction through Zave and Jackson's entailment relation. With the entailment relation, we structure a feature as a relation between three sets of descriptions: requirement, context, and specification. We show that feature interactions arise due to shared context. Secondly, we examine the literature on sources of feature interactions and conclude that inconsistencies between requirements are ultimately manifested on shared context. Finally, we study feature interaction taxonomies and show that in the characterisation of feature interactions in taxonomies, context sharing is central.