Kernel
A mathematical function used in support vector machines and other algorithms to map data into a higher-dimensional space where it becomes linearly separable.
Think of It Like This
Like realizing you can't draw a straight line to separate red and blue marbles on a table, so you throw them in the air to separate them in 3D.
The 'kernel trick' allows algorithms to operate in high-dimensional feature spaces without explicitly computing the coordinates of the data in that space. Popular kernels include Linear, Polynomial, and Radial Basis Function (RBF). This technique is incredibly powerful for modeling complex, non-linear relationships in data.