Linked from
The 12 pages that link to Kernel (linear algebra), each with the reason it gives.
Rank–nullity theoremRelated: Its dimension is the part of the domain dimension lost under the map.
Linear mapRelated: The kernel records which input directions the map collapses to zero.
Linear operatorRelated: Its kernel reveals which inputs the operator collapses.
Linear functionalRelated: Its kernel is the subspace of vectors assigned scalar zero.
Fredholm theoryRelated: Its finite dimension is one part of the Fredholm index.