Evaporation of exoplanet atmospheres Many exoplanets are found at extremely short distances from their host stars. As a result, their atmospheres receive tremendous amount of high-energy irradiation that heats and expands the upper atmospheric layers. These layers eventually escape the planet gravity, forming huge clouds of atomic hydrogen and helium around the planets. I will present new observations of such clouds around Neptune-mass exoplanets and show new evidence that these objects are a sweet spot for atmospheric escape studies. I will then address the atmospheric heating mechanism that occurs in thermospheres and triggers atmospheric escape. I will demonstrate how it is possible to probe thermospheres of transiting exoplanets using high-resolution spectroscopy and draw perspectives for a combined use of ground-based and space-borne observations in the JWST and ELT era.