A review of existing Machine Translation Approaches, their Challenges and Evaluation Metrics

Machine translation is the process of translating a natural language into another. The primary goal of machine translation is to bridge the linguistic gap between languages. A significant job that may be utilized is to extract information from texts written in different languages through machine translation (MT). Due to the remarkable developments in Machine Translation over the past several years, we have entered the era of Neural Machine Translation (NMT). A review of MT is essential for better understanding of MT in the domain of Natural Language Processing. This paper focuses on Statistical, Corpus, Example, Rule based, Transfer based, direct based and Nural Machine Translation approach, their challenges, and existing evaluation metrics such as BLEU score and Human evaluation metrics.