Abstract: M dwarfs are by far the most common stars in the Galaxy, showing the highest rocky planet occurrence among the other spectral type stars. Some of these planets orbiting M dwarfs are within the Habitable Zone (HZ). In addition, more than 60% of Ms are active, displaying thousands of flares and superflares events. Typically, in the optical these flares have durations of ~30min and peak flux ratios up to ~x70 (E~10^33.5 erg). In the UV band, the flares are shorter (a few seconds) and with larger peak flux ratios (~x14000). The Transiting Exoplanet Survey Satellite (TESS) and other ground-based time domain surveys (Evryscope, ASAS-SN) are compiling catalogs of hundreds of thousands of flares at a few minutes cadence. Very few minutes after-the-flare time-resolved spectroscopic follow-up observations are being conducted to classify flares with spectral lines temporal variation. A few UV spatial missions are planned in the next few years to get simultaneous optical and UV data from M dwarfs flares with orbiting exoplanets. Star luminosity is the key parameter to calculate the position of the HZ in a planetary system. There exists a growing interest in understanding how intensity, frequency and duration of stellar activity can impact on the habitability of an exoplanet/exomoon. Within this astrobiological perspective two main research approaches are recently emerging: a) how stellar activity alter the atmosphere of a planet, with special emphasis on ozone degradation and; b) how flares can promote/inhibit the abiotic synthesis of organic molecules of relevance for origin of (terrestrial) life (nucleobases, sugars, carboxylic acids or aminoacids). In our talk we will describe the state-of-the-art of this cross-roads discipline, and will raise the most exciting future projects to understand the impact of flares in exoplanets' habitability.