The last decade has seen the rise of spectroscopy at very high resolution (R > 25,000) obtained with telescopes on the ground to measure the chemical inventory of exoplanet atmospheres. This technique couples the ability to resolve the dense forest of molecular lines with the sensitivity to the changing planet's orbital motion, and it extracts information from spectra via cross correlation with models. While HRCCS has shown enormous potential to recognise molecular species, exploring family of models and retrieving information about abundances and temperature has proven more challenging, and working solutions have only emerged in the last two years. In this talk I will explain how high-resolution observations differ from low-resolution, the major results of the last decade in terms of infrared spectroscopy (i.e. looking for molecules), and the recent developments to measure abundances from both emission and transmission spectroscopy. Lastly, I will highlight the complementarity between space and ground-based observatories, which we are just starting to exploit and will be fully realised when coupling JWST to the ELT.