This chapter offers a comprehensive overview of big data, focusing on its classification, storage, and processing. The first section explores different categories of big data based on structure, veracity, attribute values, dimensionality, and storage. The second section examines popular data storage mechanisms, such as files and database management systems, and provides Python code for converting data between CSV and Parquet formats. The third section discusses data processing using Pandas DataFrames, highlighting their strengths and limitations. The chapter concludes with a summary, providing essential insights for managing and analyzing big data effectively.