  Angular momentum plays a crucial role in the formation of stars and planets.
It has long been noticed that parcels of gas in molecular clouds need to reduce
their specific angular momentum by 6 to 7 orders of magnitude to participate in
the building of a typical star like the Sun. Several physical processes on
different scales and at different stages of evolution can contribute to this
loss of angular momentum. In order to set constraints on these processes and
better understand this transfer of angular momentum, a detailed observational
census and characterization of rotation at all stages of evolution and over all
scales of star forming regions is necessary. This review presents the main
results obtained in low-mass star forming regions over the past four decades in
this field of research. It addresses the search and characterization of
rotation in molecular clouds, prestellar and protostellar cores, circumstellar
disks, and jets. Perspectives offered by ALMA are briefly discussed.
