Explore ground-based Extremely Large Telescopes (ELTs) and their role in rocky exoplanet science through this 12-minute conference talk by Dimitri Mawet from Caltech. Delve into high-resolution transit spectroscopy techniques, velocity shifts, and methods for detecting water and oxygen on distant worlds. Examine the potential of thermal infrared observations and discuss the competition and phasing challenges in exoplanet research. Gain insights from this presentation, part of the "Exoplanet Science Motivations for a mid-IR LIFE-like Mission" short course held at the Keck Institute for Space Studies on November 28, 2022.