The study of a finite group 
using the local subgroups
of 
.
Local group theory plays a critical role in the classification
theorem of finite groups.
Local Group Theory
See also
Sylow TheoremsExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Local Group Theory." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LocalGroupTheory.html