This document discusses sparse matrices. It defines a sparse matrix as a matrix with more zero values than non-zero values. Sparse matrices can save space by only storing the non-zero elements and their indices rather than allocating space for all elements. Two common representations for sparse matrices are the triplet representation, which stores the non-zero values and their row and column indices, and the linked representation, which connects the non-zero elements. Applications of sparse matrices include solving large systems of equations.