  The aim of this introductory article is two-fold. First, we aim to offer a
general introduction to the theme of Bose-Einstein condensates, and briefly
discuss the evolution of a number of relevant research directions during the
last two decades. Second, we introduce and present the articles that appear in
this Special Volume of Romanian Reports in Physics celebrating the conclusion
of the second decade since the experimental creation of Bose-Einstein
condensation in ultracold gases of alkali-metal atoms.
