This document discusses linear dependency and independency. It defines that vectors are linearly dependent if one is parallel to another and linearly independent if they are not parallel. It provides notes on determining linear dependency and independency based on properties of vectors and matrices. The document outlines the mathematical process of checking for linear dependency by writing vectors as a matrix, reducing it to echelon form, and identifying any zero rows. It also explains how to derive a linear dependence relation and express one vector in terms of others using this relation.