  We present main results from X-ray surveys performed with ASCA, focusing on
the ASCA Large Sky Survey (LSS), the Lockman Hole deep survey, and the ASCA
Medium Sensitivity Survey (AMSS or the GIS catalog project). The log N-log S
relations, spectral properties of sources, and results of optical
identification are summarized. We discuss implications of these results for the
origin of the CXB.
