Which social phenomenon can label an individual and influence their self-identity?

The phenomenon that can label an individual and influence their self-identity is stigma. Stigma refers to the negative labeling of individuals based on perceived characteristics that are considered socially unacceptable. This labeling can lead to feelings of shame, isolation, and a distorted self-image, affecting how individuals view themselves and how they interact with others.

When an individual is stigmatized, they may internalize the negative perceptions associated with that label, which can shape their behavior, self-esteem, and social interactions. This process is significant because it highlights how societal attitudes and judgments can impact one's identity and experiences. For instance, someone labeled as a "criminal" may internalize this stigma, which could alter their self-concept and lead to further social exclusion or deviance.

In contrast, the other options represent different sociological concepts that do not inherently focus on labeling or self-identity in the same way. Solidarity refers to the bonds that unite members of a social group, socialization is the process through which individuals learn and internalize the values and norms of their society, and assimilation involves the process by which individuals or groups of differing backgrounds come to adopt the customs and attitudes of a dominant culture. None of these concepts primarily involve the negative labeling that characterizes stigma.