A spreadsheet is a grid of columns and rows used to organize numerical data. It consists of cells formed at the intersection of each column and row. Cells can contain text, numeric constants, or formulas. Formulas begin with an equal sign and perform calculations using data from other cells. Common spreadsheet functions include SUM, AVERAGE, MAX, MIN, and COUNT. Spreadsheets allow users to track budgets, expenses, and savings over time through the use of cells, formulas, and functions.