This book gives a thorough and entirely self-contained, in-depth
introduction to a specific approach to group theory, in a large sense of
that word. The focus lie on the relationships which a group may have
with other groups, via "universal properties", a view on that group
"from the outside". This method of categorical algebra, is actually not
limited to the study of groups alone, but applies equally well to other
similar categories of algebraic objects.
By introducing protomodular categories and Mal'tsev categories, which
form a larger class, the structural properties of the category Gp of
groups, show how they emerge from four very basic observations about the
algebraic litteral calculus and how, studied for themselves at the
conceptual categorical level, they lead to the main striking features of
the category Gp of groups.
Hardly any previous knowledge of category theory is assumed, and just a
little experience with standard algebraic structures such as groups and
monoids. Examples and exercises help understanding the basic definitions
and results throughout the text.