This course paper explores the social factors that influence language variation, emphasizing the role of sociolinguistics in understanding how language fluctuates according to individual, territorial, public, and global levels. It discusses the impact of class, ethnicity, gender, culture, and context on language use and variation, highlighting the significance of these factors in language teaching and social judgment. The work includes theoretical discussions and practical examples to show how language varieties serve as the basis for social interaction and exclusion.