Matrices are rectangular arrangements of numbers, expressions, or symbols organized into rows and columns. They are used across many fields including physics for electrical circuits and optics calculations, computing for 3D graphics and encryption, geology for seismic surveys and data analysis, animation for 3D modeling and transformations, statistics and economics for presenting real-world data and calculating GDP, and other fields like data storage, robotics, analytical concepts, and software design. Matrices have wide applications in science, technology, engineering and mathematics.