The slow speed solar wind as measured at the Earth orbit and beyond is characterized by its velocity of $simeq$400 km s-1, by its coronal composition and by its frozen-in temperature (from carbon charge-states) of 1.4--1.6 ¿ 106 K. In contrast the fast speed solar wind is characterized by its velocity of $simeq$750 km s-1, its nearly photospheric composition and its frozen-in temperature of $simeq$8 ¿ 105 K. The solar wind is believed to originate very close to the solar surface, but since it is accelerated significantly above the solar surface, its velocity cannot be correlated with remote observations to trace its origin. In contrast, elemental abundances and freeze-in temperatures can be used as tracers for locating the sources from which the slow and fast solar winds emerge. By comparing remote observations with properties of the solar wind observed in situ, the most likely structures from which solar wind plasmas emerge can be identified. In the present paper we review the current understanding of the morphological features present in the solar upper atmosphere and their physical properties such as electron temperature, electron density and elemental abundances. In addition, we discuss these observations in the context of recent theories describing the emergence of new magnetic flux to power the solar wind, and more traditional models that treat the background field and solar wind as a steady phenomenon.