CMB interferometry
  Interferometry has been a very successful tool for measuring anisotropies in
the cosmic microwave background. Interferometers provided the first constraints
on CMB anisotropies on small angular scales (l~10000) in the 1980s and then in
the late 1990s and early 2000s made ground-breaking measurements of the CMB
power spectrum at intermediate and small angular scales covering the l-range
~100-4000. In 2002 the DASI made the first detection of CMB polarization which
remains a major goal for current and future CMB experiments. Interferometers
have also made major contributions to the detection and surveying of the
Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. In this short review I cover
the key aspects that made interferometry well-suited to CMB measurements and
summarise some of the central observations that have been made. I look to the
future and in particular to HI intensity mapping at high redshifts that could
make use of the advantages of interferometry.
