Structured data refers to data that is organized in a tabular format with well-defined columns and rows. It is often stored in databases, spreadsheets, or other data structures designed to be easily processed and analyzed. Examples of structured data include data from transactional systems, such as purchase histories and inventory records, and demographic data, such as age and income. Structured data can be easily input into machine learning algorithms for training and prediction. Machine learning algorithms are also optimized for structured data and can often achieve high accuracy and performance when trained on this data type.