There are some striking differences between the properties of low surface brightness (LSB) galaxies, such as UGC 128 & F563-1 and normal spiral galaxies, such as M33 and NGC 2403. LSBs have extremely high mass to light ratio (as measured by rotation curves) which implies low contribution of stars and gases to the overall mass of the galaxy. LSBs are dark-matter dominated galaxies, with over 95% of their mass as non-baryonic dark-matter. The LSBs have no central bulge (common for normal spiral galaxies) and hence have a significant amount of dark-matter in the center. The mass spectrum of star formation in LSBs consists of fewer massive stars as compared to normal spirals and thus LSBs are relatively unevolved as compared to normal spirals. The LSBs also have a rapid star formation rate. The central surface brightness of LSBs are a few order of magnitudes lower than normal spiral galaxies.