Linked from
The 7 pages that link to Fundamental theorem of Galois theory, each with the reason it gives.
GroupRelated: It displays the link between group structure and the solvability of equations.
Galois groupRelated: It converts group structure into a complete description of intermediate fields.
SubgroupRelated: It turns subgroup structure into a map of field extensions.
Field automorphismRelated: It translates subgroups of field automorphisms into intermediate fields.