SP-GiST is suitable for structures where the space can be recursively split into non-intersecting areas. This class comprises quadtrees, k-dimensional trees (k-D trees), and radix trees.
GiST is an abbreviation of «generalized search tree». This is a balanced search tree, just like «b-tree» discussed earlier.
We will now consider B-tree, the most traditional and widely used index. This article is large, so be patient.