in android, one provides four different density-specific resources.

  ldpi:  low-density screens (~120dpi)
  mdpi:  medium-density (~160dpi) [baseline]
  hdpi:  high-density (~240dpi)
  xhdpi: extra high-density (~320dpi)

there is a nodpi qualifier which is intended for density-independent resources.

there are also screen size qualifiers, small, normal, large, extra large.