  The Tomonaga-Luttinger-Liquid (TLL) has been the cornerstone of our
understanding of the properties of one dimensional systems. This universal set
of properties plays in one dimension, the same role than Fermi liquid plays for
the higher dimensional metals. I will give in these notes an overview of some
of the experimental tests that were made to probe such TLL physics. In
particular I will detail some of the recent experiments that were made in spin
systems and which provided remarkable quantitative tests of the TLL physics.
