The BR section deals with the interactions of beams with RF systems and their environment, primarily in the longitudinal plane. We work on almost all CERN synchrotrons (PSB, PS, SPS, LHC, ELENA, LEIR, …), with proton, anti-proton and ion beams, often from a Local Control Room (Faraday cage) or the CERN Control Centre (CCC). The support of beam operation and machine developments has the highest priority. The BR section members are strongly involved with performance improvements (e.g. mitigating longitudinal instabilities) and upgrades of existing accelerators (e.g. RF systems in LHC injectors, impedance reduction, …). Significant effort is invested in the design and production of new RF systems (including HL-LHC crab cavities) for existing and future CERN rings. Our team is able to measure and calculate the impedance of various machine elements using many different methods, including beam measurements (see picture). Beam diagnostics in the longitudinal plane (bunch profiles, phase space tomography, Beam Quality Monitors, Schottky spectra…) are also our field of interest and support. We are developing the Beam Longitudinal Dynamics code (BLonD) which is heavily used in numerous particle simulations, vital to support beam measurements, RF manipulations and to predict beam performance after upgrades. Important contributions are made to the LIU and HL-LHC projects. Our section, in addition to seven staff members, has many fellows and PhD students and we rely heavily on their work. We also appreciate the help from our external collaborators, summer and technical students, as well as from the interns.