Nicolas Bourbaki is the collective pseudonym under which a group of (mainly French) 20th-century mathematicians wrote a series of books presenting an exposition of modern advanced mathematics, beginning in 1935. With the goal of founding all of mathematics on set theory, the group strove for rigour and generality. Their work led to the discovery of several concepts and terminologies still discussed. Bourbaki congress, 1938.
While Nicolas Bourbaki is an invented personage, the Bourbaki group is officially known as the Association des collaborateurs de Nicolas Bourbaki (Association of Collaborators of Nicolas Bourbaki), which has an office at the École Normale Supérieure in Paris.
After Cauchy, Fourier, Galois, French-Math dominance in 17th & 18th centuries had been overtaken in 19th century by their defeated enemy: Germany, which produced the "Prince of Math" (Gauss), his bright students and the great Gottingen successors (Riemann, Dedekind, Cantor, Kronecker, Wierestrass, Hilbert, Felix Klein, Lindermann, etc).
Before World War I, a group of Ecole Normale Superieure students headed by Andre Weil, realised that French Math Textbooks were outdated and thus decided to form a math-study group nicknamed "Bourbaki". This group met regularly in the cafe near Jardin de Luxembourg in Paris, with the intention of rewriting the entire Mathematics based on the new SET Theory by Cantor, and followed the example of Euclid's 13-volume "Elements of Geometry". Their huge volumes were called "Elements of Mathematics" (Les Elements de Mathematiques).
The Bourbaki books are what the beatles were to rock - fundamental in terms of conciseness and precision.