We build applications to address problems in our daily lives. People build online shopping websites so we can order clothes and books online. They build human resources software so companies can manage employees. And they build text-processing software so we can edit documents. From the application-development perspective, no matter what problems our application addresses, we must extract and process information about the problems. In programming, to model various kinds of information in our applications, such as product descriptions and employees, we must use proper data structures. These data structures provide a standardized way to represent real-life entities in our applications, making it possible to enable specific rules, organizations, and implementations to address our business needs. In this part, we focus mainly on using built-in data models, including strings, lists, tuples, dictionaries, and sets. Moreover, you learn techniques that are shared by various types of data structures, such as sequence-like data and iterables.