The Milky Way Galaxy offers a unique opportunity to study the structure
and contents of a major stellar system in three dimensions, at high
spatial and spectral resolution, and to very large galactocentric
distances. This potential can be realised only by statistical surveys of
large areas of the sky, and by detailed study of specific regions with
exceptional properties, such as the Galactic centre, and of specific
classes of object, such as the globular clusters. The acquisition of
such data from a variety of ground-based and satellite surveys has been
a primary topic of Galactic research for some years. Several such
surveys have been completed recently, and have led to a substantial
modification of our understanding of Galactic structure and evolution.
The importance of the ability of satellite observatories to survey and
to study wavelengths which are inaccessible from the ground is evident
in the wealth of data discussed and analysed in this volume which is
derived from satellites, specifically COS-B, HEAD-I, HEAO-3, IRAS,
PIONEER-lO, SAS-2, and TENMA. The cru- cial role of ground-based
observations to complement and comprehend the satellite data is also
well evident. Similarly, the major ground-based studies whose results
are reported here illustrate the necessity for carefully conceived and
executed very large scale surveys of many types of object and many parts
of parameter space before a coherent picture of the Galaxy will be
available.