  We present results obtained from the studies of magnetic activities on four
solar-type stars (F-type star KIC 6791060, K-type star LO Peg, and two M-type
planet-hosting stars K2-33 and EPIC 211901114) by using optical observations
from several ground- and space-based telescopes. In this study, we investigate
magnetic activities such as spot-topographic evolution and flaring events in
these stars. We compare the results obtained from this study with that of the
Sun. In the surface temperature maps, one active longitude has been detected in
KIC 6791060, whereas in each of the other three cases two active longitudes are
seen. The spottedness was found to vary in the range of 0.07--0.44%, 9--26%,
3.6--4.2%, and 4.5--5.3% for KIC 6791060, LO Peg, K2-33, and EPIC 211901114,
respectively. Several flaring events have been identified in each star. An
increasing trend in flaring frequency per stellar rotation has been found in
the stars with a change in spectral type from F to M. These findings indicate
the increase in magnetic activities with the spectral type of stars. This can
be explained due to increasing the ratio of the thickness of the convection
zone to the radiation zone from F-type star to the M-type stars.
