X-ray observations of hot gas in galaxy clusters revealed a variety of physical processes occurring on a broad range of spatial scales. Understanding the physics of these processes is important for cluster cosmology, studying of the evolution of the most massive galaxies and radio-mode AGN feedback, testing plasma kinetic theory. The advancement in observations and theory led to significant progress in the field over the past decade. However, despite the progress, many important questions remain poorly understood. What are the properties of turbulence and bulk motions of the gas? How valid is the assumption of hydrostatic equilibrium and how strong is the mass bias? What is the microphysics of radio-mode AGN feedback and how does it prevent vigorous star formation in cluster cores? How important are transport processes, such as gas viscosity and thermal conduction? And how magnetic fields affect the properties of thermal gas? In my talk, I will discuss recent progress that has been done to resolve some of these problems. In particular, I will show how X-ray images of galaxy clusters can be used to measure velocity power spectra and the equation of state of gas perturbations driven by the black hole - hot gas interaction. I will highlight recent results from new, high-resolution spectral data from the Hitomi satellite. Finally, I will discuss near and more distant future perspectives in the field.