Krashen's Input Hypothesis is a theory in second language acquisition proposed by linguist Stephen Krashen. It suggests that language learners acquire new language skills most effectively when they are exposed to language input that is slightly above their current proficiency level, known as "i+1." This means that learners should understand most of the input but still encounter new vocabulary or structures that challenge them. The hypothesis emphasizes the importance of meaningful communication and context in learning. According to Krashen, when learners receive comprehensible input, they can naturally absorb the language, leading to better acquisition compared to traditional methods focused on grammar rules and memorization.