A dense matrix is a type of matrix in which most of the elements are non-zero. This contrasts with sparse matrices, where a significant number of elements are zero. Dense matrices are commonly used in various fields, including computer science, engineering, and mathematics, due to their straightforward representation and ease of computation. In a dense matrix, operations such as addition, multiplication, and inversion can be performed efficiently because all elements are stored and accessed. They are typically represented in a two-dimensional array format, making them suitable for applications like linear algebra and machine learning, where complete data representation is essential.