Fluctuations are usually invoked to explain the anomalous transport in tokamaks. The main observations regarding fluctuating quantities obtained in a wide range of experiments are summarised. Fluctuations are turbulent with broad wavenumber and frequency spectra, the wavenumber being such that kχL, < 1 and frequencies in the diamagnetic drift frequency range. Density, potentiel and temperature (electrostatic) fluctuations at the edge are generally observed to account for particle and energy transport. This direct comparison cannot be done in the core because of the limited available measurements, and fluctuation driven transport is to be estimated through the various theories. However the fluctuation level is generally observed to be correlated with the transport properties in a wide range of regimes. In particular in improved confinement regimes with transport barriers, turbulence is drastically reduced, magnetic/velocity shear are identified as the control parameters.