$b\to s\mathrm{\ell }\mathrm{\ell }$ and Lepton Universality at LHCb

Lepton universality, meaning the equal coupling of the electroweak gauge bosons to the different lepton flavours, is a central property of the Standard Model (SM). Tests of lepton universality in ratios of rates of $b\to s{\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ decays involving electron and muon final states profit from precise SM predictions, free from hadronic uncertainties. They therefore constitute particularly powerful probes for New Physics (NP) scenarios. These proceedings summarise the latest and most precise tests of lepton universality in rare $b\to s{\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ transitions by the LHCb collaboration.