This document provides a summary of approaches for performing sentiment analysis. It discusses document-level, sentence-level, and aspect-level sentiment analysis. At the document level, the entire document is classified as positive or negative. At the sentence level, each sentence's sentiment is determined. At the aspect level, the sentiments expressed towards specific aspects are identified. The document also outlines applications of sentiment analysis such as in e-commerce, brand/customer feedback analysis, and government use. Finally, it discusses sentiment classification approaches and levels.