Indicates that the challenge involves the manipulation of binary matrices, matrices whose elements are all one of two possible values, typically 1 and 0, or True and False.
A binary matrix is a matrix where all elements are one of two possible values, typically \$0\$ and \$1\$. Challenges with this tag typically ask about determining patterns in matrices, or about generating such matrices. All challenges with this tag should include a description of the values used in the matrix.
The matrix tag is unnecessary for challenges tagged with binary-matrix, and grid often overlaps.