  The polarization of the Cosmic Microwave Background (CMB) radiation carries
essential information on early stages of the Universe such as the cosmic
inflation, forming cosmological structures through gravitational lensing, and
the epoch of re-ionization. The signal requires high sensitivity instruments
with a large number of detectors (bolometers) and low leakage of Stokes $I$
into $Q$ and $U$. The Galactic diffuse foreground emission is a limiting factor
in CMB polarization measurements, requiring its characterization at both low
and high frequency compared to the peak of the CMB emission, in order to be
subtracted off. In this paper we describe the next generation space experiment
for the measure of the CMB polarization, LiteBIRD, that is aimed to investigate
the first fractions of a second of the Universe and is expected to be flown at
the beginning of the next decade. Also, we describe the experiments designed
for measuring the foreground emissions from our own Galaxy. Finally, we also
describe sub-orbital experiments, operating and planned, as they are vehicles
for the development of technologies and data reduction tools that have been and
will be used in space missions.
