Web2.0 has contributed tremendously towards the rapid growth of web contents which ensures that customers utilize existing blogs, discussion forums, e-commerce and many other sites to express their opinions and read reviews of other people on different products and services which they plan to procure. Such an online wealth of information over the web has helped customers, firms, manufacturers, service providers, social and government units to take proper decision to procure or enhance various products and services. This practice has triggered the need to enhance existing methods and techniques to extract and summarize opinions from different online reviews. This paper surveys recent and leading methods and techniques that are used for opinion mining and then outlines available resources which have been developed in this regard. The paper also presents few challenges and open issues that need to be addressed and researched in more depth in order to improve the way opinions are extracted and summarized to users and other interested groups
