Drawn from the lessons learned in an application for the subway company in Paris, we pointed out that operators used practices instead of the procedures developed by the company, practices appearing like contextualization of the procedures taking into account specificity of the task at hand and the current situation. This leads us to propose, first, a working definition of context at a theoretical level, and, second, its implementation in a software called Contextual Graphs. In this paper, we present the results of the complete loop, showing how the theoretical view is intertwined with the implemented one. Several results of the literature are discussed too. Beyond this internal coherence of our view on context, we consider knowledge acquisition, learning and explanation generation in our framework. Indeed, these tasks must be considered as integrated naturally with the task at hand of the user.