  Low-mass stars belonging to the M spectral type are the most numerous stars
in our Galaxy, amounting to about two-thirds in number, and are found at the
bottom of the main sequence in the H-R diagram. %Multi-wavelength studies on
star-forming regions help to understand the census of PMS stars, their
formation process, and the interaction of expanding H II regions harboring
massive stars with their natal molecular clouds. Photometric studies of
low-mass stars, including brown dwarfs (BDs), provide several important
evolutions of their atmosphere, magnetic flares and chromospheric activity.
This paper highlights a few interesting results from our optical I-band
observations of 2MASS J03435638+3209591 in the young star-forming IC~348 region
and three BDs in Taurus star-forming regions using ground-based telescopes as
well as a space-based telescope. We estimated the fast periodicities in the
range of 1.5 to 3 hours in Taurus BDs. Furthermore, using the long-term
photometry from the Transiting Exoplanet Survey Satellite (TESS), we have
conducted a time-resolved variability analysis of CFHT-BD-Tau 4. The
periodogram analysis of TESS data reveals an orbital period of $\sim$ 3 days.
We found two flare events in TESS sector 43 data for this BD and estimated the
flared energies as $4.59\times10^{35}$ erg and $2.64\times10^{36}$ erg, which
sit in the superflare range.
