A central theme in second language acquisition is Interlanguage, an idea grounded on the concept that the human brain activates an innate psychological structure in a second language learning process. It is a system that is constructed by second language learners. There is a distinct language system in second language learners’ utterances which is quite different from the native speakers (Selinker 1972, p. 209-241). Interlanguage varies under diverse contexts, e.g., one domain of IL can be different from another one in terms of fluency, accuracy, and complexity. However, interlanguage can cease developing or fossilize, in any of its developmental stages due to the complexities a learner faces in acquiring a second language. According to Mitchell et al. (2013, p.60), under the platform of interaction, feedback, modified input, negotiation for meaning, and modified input come together to facilitate second language acquisition. It is evident from this point that Feedback and Negotiation are interrelated. This paper proposes to discuss these two subjects under the umbrella term interaction and argues the role of both of them on interlanguage development, concluding with an analysis of these techniques and the pedagogical implications.