Public opinion is the collective opinion on a specific topic or voting intention relevant to society. It is the people's views on matters affecting them. The term originates from France, and first appeared in the 17th century, though writers had identified the importance of the opinion of the people long before this. Prior to the advent of mass media, public fora such as coffee houses and gentlemen's clubs were used as exchanges of opinion and some reputable locations had great influence.

In the 21st century, public opinion is widely thought to be heavily influenced by the media, and many studies have been undertaken which look at the different factors which influence public opinion. Politicians and other people concerned with public opinion often attempt to influence it using advertising or rhetoric. One of the struggles of public opinion is how it can be influenced by misinformation.