Cannabis has been used by humans as a medicine, intoxicant, food, and fiber for millennia. In fact, recent archeological evidence suggests that Cannabis was possibly the first species domesticated by humans. In modern times, medicinal Cannabis and isolated phytocannabinoids have shown efficacy in numerous therapeutic indications, including pain, nausea, wasting syndrome, and epilepsy. The past decade has seen a surge in patient access to medicinal Cannabis products in the United States (US) and elsewhere. The lack of federal regulations in the US has created a complex market that is distinctive in many ways from other contemporary medicinal product markets. This situation has pros and cons. For example, pros include patient empowerment, product diversity, and rapid product innovation, whereas cons include a lack of evidence-based practices and often variable product standards. The complexity of the situation can create confusion for health-care providers tasked with serving medicinal Cannabis users. To assist in navigating this evolving field, this chapter presents an overview of medicinal Cannabis topics for health-care providers and other interested stakeholders. Topics covered include history, nomenclature, common medicinal Cannabis formulations, product labeling issues, an overview of the chemical components of Cannabis, the endogenous endocannabinoid system, pharmacokinetics and pharmacodynamics of common phytocannabinoids such as (−)-trans-Δ9-tetrahydrocannabinol (Δ9–THC) and cannabidiol, an overview of existing FDA-approved cannabinoid products, and finally a discussion of common adverse effects associated with Cannabis.