Abstract
The Web provides excellent opportunity to express views/opinions about organizations, events, individual, government, products and services in newsgroups, feedback emails and review websites. The web is indeed a rich 'words-of-mouth' source. People's online opinions highly influence customers purchase decisions and manufacturers policies. It is time consuming to get decision oriented information from large and massive online reviews. Opinion mining addresses this problem by analyzing and presenting online reviews in effective ways. Researchers have been proposed different opinion mining systems. In this paper, authors designed evaluation metrics for the phases of opinion mining to compare noteworthy opinion mining systems.