In Colombian law, possession and retention have been classified in different fashions, including as mere legal facts, as a means of defense or even as veritable property rights.Beyond the terminological difficulties, this situation has caused a real problem of legal uncertainty.For example, we may pose the questions: do possession and retention enjoy general or special recognition?Under what conditions are these institutions valid?Do they offer direct powers over property?Do they provide some form of defense?Can they circulate in the market?By way of introduction we will present i. a justification of the essay and ii.an initial approximation to the institutions of possession and retention.