As mentioned, k-nearest neighbor, a x-dimensional similarity search algorithm (you can write this in python in like 25 lines, honest to god).
ANN, artificial neural network, which is what things like tensorflow were borne. Neural networks were kind of passe before they were revived by "deep learning"; their essentially a self-correcting, self-referencing set of logic gates.
k-nearest neighbors (the k is just the number of nearby data points you consider when classifying a point), a clustering algorithm, and artificial neutral network
