OMG Thank you! I'm going through tons of linear algebra for a ML algorithm I need to understand and matrix multiplication is ... weird to say the least.
I strongly recommend 3blue1brown's intro to linear algebra[0] for quick intuitions, followed by Gilbert Strangs MIT Open Course[1][2] for (much) deeper detail. Strang is a genius, but Sanderson's graphics and intuitions can be helpful early on.
