With the advent of Web 2, the required platform for commenting and sharing it in web space was provided for users, and it became a part of the daily activities of the users in cyberspace. Besides that, the emergence of social networks and boom of these networks intensified these activities, and today users' comments are frequently found in cyberspace. Unlike the past, users can easily express their views on political, sporting, or economic events, or they can even comment on a commodity they have bought and share their satisfaction or dissatisfaction of the purchased goods and make it available to other users. Today, prior to buying a product, every person looks for the comments of those who have purchased and used this product. All these reveal the importance of opinion mining field. Opinion mining (OM) area looks for a way to classify these comments. This is because due to the high volume of these opinions, one cannot manually review and sum up these comments, and the advantages of today's technologies must be used to analyze and classify these comments. Sciences such as data mining, text mining, and the methods used in natural language processing are used for OM.