The [[Nullity]] of a [[Matrix]] $A$ is the [[Dimension]] of the [[Nullspace]] of $A$, in other words, the number of columns *without* a leading term in the [[Reduced Row Echelon Form]] of $A$. $\huge \forall A \in M_{n\times m} : \op{rank}(A) + \op{nullity}(A) = m $ >[!info] Tip > Nullity can be thought of how much information is lost in a [[Linear Transformation]]