  This article is devoted to a discussion of stripe and electron-nematic order
and their connection to electronic properties in the pseudogap regime of
copper-oxide superconductors. We review basic properties of these
symmetry-breaking ordering phenomena as well as proposals which connect them to
quantum-oscillation measurements. Experimental data indicate that these orders
are unlikely to be the cause of the pseudogap phenomenon, implying that they
occur on top of the pseudogap state which itself is of different origin.
Specifically, we discuss the idea that the non-superconducting pseudogap ground
state hosts electron-like quasiparticles which coexist with a spin liquid,
realizing a variant of a fractionalized Fermi liquid. We speculate on how
stripe order in such a pseudogap state might offer a consistent description of
ARPES, NMR, quantum-oscillation, and transport data.
