With the tremendous growth of social networks, there has been a growth in the amount of new data that is being created every minute on these networking sites. The notion of community in this social networking world has caught lots of attention. Studying Twitter is useful for understanding how people use new communication technologies to form social connections and maintain existing ones. We analysed how geo-tagged tweets in Twitter can be used to identify useful user features and behavior as well as identify landmarks/places of interests. We also analysed several clustering algorithms and proposed different similarity measures to detect communities.