Summary: Homogeneous gravitational wave backgrounds arise as infinite momentum limits of many geometries with a well-understood holographic description. General global aspects of these geometries are discussed. Using exact CFT techniques, strings in pp-wave backgrounds supported by a Neveu-Schwarz flux are quantized. As in euclidean \(AdS_{3}\), spectral flow and associated long strings are shown to be crucial in obtaining a complete spectrum. Holography is investigated using conformally flat coordinates analogous to those of the Poincaré patch in AdS. It is argued that the holographic direction is the light-cone coordinate \(u\), and that the holographic degrees of freedom live on a codimension-one screen at fixed \(u\). The usual conformal symmetry on the boundary is replaced by a representation of a Heisenberg-type algebra \(H_{D} \times H_{D}\), hinting at a new class of field theories realizing this symmetry. A sample holographic computation of two- and three-point functions is provided and Ward identities are derived. A complementary screen at fixed \(v\) is argued to be necessary in order to encode the vacuum structure.