The Natural Approach is a language teaching method developed by Stephen Krashen and Tracy Terrell in 1983 that focuses on acquiring a second language naturally. It believes adults can acquire a new language in the same way children do, through meaningful interaction and comprehension of messages rather than conscious learning of grammar rules. The key principles are the Acquisition-Learning Hypothesis, the Monitor Hypothesis, the Natural Order Hypothesis, the Input Hypothesis, and the Affective Filter Hypothesis. The teacher's role is to create a low-anxiety environment where students can engage in activities using the target language, while students respond through physical actions and interaction at early stages.