Dwarf galaxies are fascinating objects under many respects: as dark matter 
probes, since they appear to be the smallest galactic systems requiring the 
presence of dark matter; as the most numerous type of galaxies; but also 
because of the impressive variety of properties exhibited by such small 
systems. 

As larger galaxies, dwarf galaxies can be broadly classified into different 
types according to properties such as gas content, star formation histories and 
optical appearance. 

Understanding what caused the variety of dwarf types we see today, and whether 
they can fit in a common evolutionary framework, gives us important information 
on the mechanisms that drive galaxy evolution at the low galactic mass end. 

The Local Group is a great laboratory for such studies, since it contains 
dozens of dwarf galaxies that can be studied in great detail from their 
resolved stellar populations, with representatives from the various existing 
types. 

Here I will give an overview of the properties of Local Group dwarf galaxies, 
as obtained from wide-area photometric and spectroscopic surveys.