  Let $\mathfrak g$ be a complex simple Lie algebra and $\mathfrak b=\mathfrak
t\oplus\mathfrak u^+$ a fixed Borel subalgebra. Let $\Delta^+$ be the set of
positive roots associated with $\mathfrak u^+$ and $\mathcal K\subset\Delta^+$
the Kostant cascade. We elaborate on some constructions related to $\mathcal K$
and applications of $\mathcal K$. This includes the cascade element
$x_{\mathcal K}$ in the Cartan subalgebra $\mathfrak t$ and properties of
certain objects naturally associated with $\mathcal K$: an abelian ideal of
$\mathfrak b$, a nilpotent $G$-orbit in $\mathfrak g$, and an involution of
$\mathfrak g$.
