Sentiment analysis works in social media marketing by utilizing natural language processing (NLP) and machine learning algorithms to assess and interpret public opinion. It analyzes user-generated content, such as comments and reviews, to categorize sentiments as either positive, negative, or neutral. By extracting insights from this data, businesses can gauge customer perception of their brand, products, or services. This analytical approach enables companies to adjust their marketing strategies, enhance customer engagement, and address negative feedback proactively, ultimately improving overall brand reputation.