Spreadsheet programs allow users to enter numeric data into a grid of rows and columns called a worksheet. This data can then be used for calculations using formulas. Formulas begin with an equal sign and can reference cell addresses to perform operations like addition, averaging, finding the highest/lowest values. Common spreadsheet functions make complex calculations easier. Spreadsheets save data for future use and allow visualization through charts and tables. They are useful for tasks like accounting, data analysis, and personal finance management.