Abstract: Over the past decade, periodic drives have been shown to induce novel dynamical phases of matter that exhibit properties not found in ground-state systems. In this talk, we will discuss signatures of such drive-induced phases on the (d+1)-dimensional Floquet lattice, comprised of d spatial dimensions plus the frequency domain. We will show that the average position of Floquet eigenstates along the frequency axis is given by a non-adiabatic Berry phase, which can be interpreted as frequency-domain polarization. Whenever this polarization is quantized to a nontrivial value, the phase of matter cannot be continuously connected to a time-independent state and, as a consequence, it captures robust properties of its dynamics. We will illustrate this in driven topological phases, such as disordered superconducting wires and the anomalous Floquet Anderson insulator, as well as in driven symmetry-broken phases, such as time crystals. We will further introduce a new dynamical phase of matter that is constructed by imposing quantization conditions on its frequency-domain polarization. This illustrates the potential for using this kind of polarization as a tool to search for new driven phases.