Twitter is a micro-blogging site used by people to express their opinions on various topics. Sentiment Analysis is the process of extracting meaningful customer insight from a text in terms of sentiment score. Twitter Sentiment analysis is an application of sentiment analysis, on the twitter data (tweets).But today it has become difficult to analyze tweets because of the changed and challenging formats of the tweets. The increase in the use of various slangs, emoticons, abbreviations, and puns in tweets, has made it difficult to analyze tweets in the same ways as before. In this paper, we aim to review some papers regarding research in sentiment analysis on Twitter, describing the methodologies adopted and models applied; along with describing Vader Sentiment Analysis which is a Python-based approach.