摘要：Implicit knowledge acquisition is the goal of second language (L2) learning. Ellis (2006;2009) argues that it is implicit rather than explicit knowledge which underlines linguistic competence reflected in actual speech production and comprehension. Thus, this review aims to elucidatethe theoretical nature of implicit and explicit linguistics knowledge and how these types of knowledge are distinguished in terms of their representation and processing in use. The overall goal is to make the understanding of implicit knowledge easier to a wide audience of L2 researchers, especially those who are not interested in the absence of awareness of the target feature to be learnt at the point of learning.