STM is one of the most useful instruments to probe the morphology of the surface along with the real space electronic properties through a sharp metallic tip by following the quantum mechanical tunneling effect. Since STM is very sensitive to the local electronic density (LDOS) of the material, a small change in the composition of the adsorbate or structure of the material can be captured by STM. STM has been widely applied in research and manufacturing in fields spanning from biology to material science to microelectronics. It can be used to image topography, measure surface properties, manipulate surface structures, and initiate surface reactions. The STM is an important tool in nanotechnology enabling accurate measurement of feature dimensions on the atomic scale, as well as moving and placing atomic-scale building blocks at specific locations on a surface. With the increase of nanoscale surface properties, the STM is capable of probing the spin-orbit coupling effect in strongly correlated systems, spin-dependent DOS of magnetic thin films, etc. with great accuracy along with real-space imaging.