Twitter, a popular social media platform, provides huge volume of useful information. This talk demonstrates that Twitter data can be analysed easily with R and provides examples for such an analysis. Twitter data can be extracted with package twitteR. After that, tweets can be cleaned and analysed with package tm for text mining and with package topicmodels for topic modelling. Sentiments of tweets can be analysed with package sentiment140. Relationship between Twitter users can be analysed with package igraph for social network analysis. The methodology and techniques used are generic and can be easily applied to analysis of other Twitter accounts.