A poison is generally defined as a substance that, upon introduction to a living organism, exerts toxic effects, ranging from minor impairment to acute systemic failure. Toxicology is the branch of science dedicated to the study of these chemical agents and their biological effects. Toxicity is highly dependent on dose, a concept formalized by the dose-response relationship, wherein adverse effects usually increase proportionally with the concentration of the substance. Mechanisms of poisoning are diverse, involving interference with essential biochemical pathways, disruption of cellular membranes, or inhibition of critical enzyme systems. Modern research focuses on identifying molecular targets, understanding metabolism, and developing antidotes or treatments to mitigate the harmful impact of xenobiotics on biological processes.