Given a
prime number p, a
p-group P is a
mathematical group all elements have a power of
p as their order (that is, for each
g in
P, there exists an integer
n such that
g to the power
pn is equal to 1, while
gm is not 1 for any
m<
pn). If
G is finite, this implies that the order of
G (the number of its elements) is itself a power of
p.
Quite a lot is known about the structure of finite p-groups. One of the first standard results is that the center of a finite p-groups cannot be the trivial subgroup {1}.