Strangeness signature of of quark-gluon plasma (QGP) is central to the
exploration of baryon-dense matter: the search for the critical point and onset
of deconfinement. I report on the discovery of QGP by means of strangeness: The
key historical figures and their roles in this quest are introduced and the
experimental results obtained are discussed. The important role of antihyperons
is emphasized. The statistical hadronization model, and sudden hadronization
are described. Results of present day data analysis: strangeness and entropy
content of a large fireball, and the universal hadronization condition
describing key features of all explored collision systems are presented.Comment: 27 pages, 9 figures, Based on two invited lectures presented at CPOD
(Critical Point and Onset of Deconfinement) International Conference held in
Wroclaw, Poland May 30th --June 4th, 2016, dedicated to Marek Ga\'zdzicki on
occasion of his 60th birthday, v2: shortened upon request of editor