This lecture covers the analysis of energy flux in turbulence, focusing on the scale-by-scale energy budget and the writing of flux in terms of third-order velocity increment moments. It also discusses the low-pass filled velocity via Faris - Granulation and the Kasman-Howarth-Monin relation. The lecture delves into the concepts of homogeneous and isotropic turbulence, the Kolmogorov theory, and the restoration of symmetries at different scales.