Abstract: With the increasing sites for forums, online reviews and social networking, the current trend is to look up reviews, expert opinions and discussions on the Web, so that the user can make an informed decision. Sentiment analysis, also known as opinion mining is the computational study of opinions, sentiments and emotions expressed in natural language processing and text analysis. A basic task is classifying the polarity of a given text at the document or sentence, whether the expressed opinion in a document or a sentence is positive, negative, or neutral. It can help better understand the behavioral patterns of users in social media for applications. First, the behavior of individuals is collected through their unstructured posts in a forum. Second, they are classified as positive/negative posts and perform the clustering. Third, the cases are encoded in terms of features in some numerical form, requiring a transformation from text to numbers and assign the positive and negative values to each word to classify the word in the document. Data are collected from forums.digitalpoint.com which includes a range of 75 different topic forums.