To factor the expression \( d^4 - d^3 \), we first identify the greatest common factor (GCF) of the two terms.
The terms \( d^4 \) and \( d^3 \) both have a common factor of \( d^3 \). We can factor \( d^3 \) out from both terms:
\[ d^4 - d^3 = d^3(d - 1) \]
Thus, the factored form of the expression is:
\[ d^3(d - 1) \]