This document discusses the distinction between implicit and explicit learning and knowledge in second language acquisition. It provides definitions and perspectives from various cognitive psychologists and SLA researchers. Implicit learning occurs unconsciously without attention to rules, resulting in intuitive knowledge, while explicit learning involves conscious memorization of rules and facts. Implicit knowledge guides automatic behaviors while explicit knowledge requires controlled processing. SLA research has found that explicit learning and knowledge are generally more effective for L2 mastery than implicit learning alone.