What is krashen's monitor model?

Krashen's Monitor Model is a theory of second language acquisition that posits that language learning involves two distinct processes: acquisition and learning. Acquisition occurs naturally through meaningful communication, while learning involves formal instruction and conscious understanding of grammar rules. The "monitor" refers to the ability to use learned knowledge to edit or correct spoken or written language, but it can only be used under certain conditions, such as sufficient time and focus on form. Krashen emphasizes that acquisition is more effective for achieving language fluency than learning.