  The electrons are an essential particle species in the solar wind. They often
exhibit non-equilibrium features in their velocity distribution function. These
include temperature anisotropies, tails (kurtosis), and reflectional
asymmetries (skewness), which contribute a significant heat flux to the solar
wind. If these non-equilibrium features are sufficiently strong, they drive
kinetic micro-instabilities. We develop a semi-graphical framework based on the
equations of quasi-linear theory to describe electron-driven instabilities in
the solar wind. We apply our framework to resonant instabilities driven by
temperature anisotropies. These include the electron whistler anisotropy
instability and the propagating electron firehose instability. We then describe
resonant instabilities driven by reflectional asymmetries in the electron
distribution function. These include the electron/ion-acoustic, kinetic
Alfv\'en heat-flux, Langmuir, electron-beam, electron/ion-cyclotron,
electron/electron-acoustic, whistler heat-flux, oblique
fast-magnetosonic/whistler, lower-hybrid fan, and electron-deficit whistler
instability. We briefly comment on non-resonant instabilities driven by
electron temperature anisotropies such as the mirror-mode and the
non-propagating firehose instability. We conclude our review with a list of
open research topics in the field of electron-driven instabilities in the solar
wind.
