Krashen's Input Hypothesis proposes that students can learn a language through comprehensible input by listening and reading alone, without the need for speaking. Research found that students learning English through input performed as well or better than those learning through traditional audiolingual methods. The hypothesis suggests that reading provides vocabulary growth in early stages, while conversation is better for later stages. Total Physical Response and input flooding expose students to language through listening and reading, while enhanced input highlights specific forms to learn. Processing instructions also focus on comprehension and outperformed traditional production-based learning.