Conformity is the act of matching attitudes, beliefs, and behaviors to group norms, politics or being like-minded. Norms are implicit, specific rules, shared by a group of individuals, that guide their interactions with others. People often choose to conform to society rather than to pursue personal desires - because it is often easier to follow the path others have made already, rather than forging a new one. This tendency to conform occurs in small groups and/or in society as a whole, and may result from subtle unconscious influences (predisposed state of mind), or from direct and overt social pressure. Conformity can occur in the presence of others, or when an individual is alone. For example, people tend to follow social norms when eating or when watching television, even if alone.

Changing our behaviors to match the responses of others, which is conformity, can be conscious or not. People have an intrinsic tendency to unconsciously imitate other’s behaviors such as gesture, language, talking speed, and other actions of the people they interact with. There are two other main reasons for conformity: informational influence and normative influence. People display conformity in response to informational influence when they believe the group is better informed, or in response to normative influence when they are afraid of rejection. When the advocated norm could be correct, the informational influence is more important than the normative influence, while otherwise the normative influence dominates. A meta-analysis of 125 Asch-type conformity wrote that normative influence is likely to occur when people make direct contact with the majority while informational influence is likely to occur when people make indirect contact with the majority.

People often conform from a desire for security within a group, also known as normative influence—typically a group of a similar age, culture, religion or educational status. This is often referred to as groupthink: a pattern of thought characterized by self-deception, forced manufacture of consent, and conformity to group values and ethics, which ignores realistic appraisal of other courses of action. Unwillingness to conform carries the risk of social rejection. Conformity is often associated in media with adolescence and youth culture, but strongly affects humans of all ages.

Although peer pressure may manifest negatively, conformity can be regarded as either good or bad. Driving on the conventionally-approved side of the road may be seen as beneficial conformity. With the appropriate environmental influence, conforming, in early childhood years, allows one to learn and thus, adopt the appropriate behaviours necessary to interact and develop "correctly" within one's society. Conformity influences the formation and maintenance of social norms, and helps societies function smoothly and predictably via the self-elimination of behaviors seen as contrary to unwritten rules.

According to Herbert Kelman, there are three types of conformity: 1) compliance(which is public conformity and it is motivated by the need for approval or the fear of being disapproval; 2) identification (which is a deeper type of conformism than compliance); 3) internalization(which is to conform both publicly and privately).

Major factors that influence the degree of conformity include culture, gender, age, size of the group, situational factors, and different stimuli. In some cases, minority influence, a special case of informational influence, can resist the pressure to conform and influence the majority to accept the minority's belief or behaviors.