[tptacek]

Their most recent post about kernels is even better than this:

https://www.dhruvonmath.com/2019/04/04/kernels/

The matrix/function stuff is elementary enough that I understand it intuitively (I suck at math), although it's neat to be reminded that given a enough independent points you can reconstruct the function (this breaks a variety of bad ciphers, sometimes including ciphers that otherwise look strong).

The kernel post actually does some neat stuff with the kernel, which I found more intuitively accessible than (say) what Strang does with nullspaces.