  We present results from a large, high-spatial-resolution near-infrared
imaging search for stellar and sub-stellar companions in the Taurus-Auriga
star-forming region. The sample covers 64 stars with masses between those of
the most massive Taurus members at ~3 M_sun and low-mass stars at ~0.2 M_sun.
We detected 74 companion candidates, 34 of these reported for the first time.
Twenty-five companions are likely physically bound, partly confirmed by
follow-up observations. Four candidate companions are likely unrelated field
stars. Assuming physical association with their host star, estimated companion
masses are as low as ~2 M_Jup. The inferred multiplicity frequency within our
sensitivity limits between ~10-1500 AU is 26.3(+6.6/-4.9)%. Applying a
completeness correction, 62(+/-14)% of all Taurus stars between 0.7 and 1.4
M_sun appear to be multiple. Higher order multiples were found in
1.8(+4.2/-1.5)% of the cases, in agreement with previous observations of the
field. We estimate a sub-stellar companion frequency of ~3.5-8.8% within our
sensitivity limits from the discovery of two likely bound and three other
tentative very low-mass companions. This frequency appears to be in agreement
with what is expected from the tail of the stellar companion mass ratio
distribution, suggesting that stellar and brown dwarf companions share the same
dominant formation mechanism. Further, we find evidence for possible evolution
of binary parameters between two identified sub-populations in Taurus with ages
of ~2 Myr and ~20 Myr, respectively.
