The aim of this paper is to identify the characteristic features, in terms of geophysically measured parameters, of the hot spot sites over the Earth's surface. We use a pattern recognition approach which identifies associations as well as single parameters, and our statistical algorithm allows us to work at a given significance level, avoiding any overfit. We use the following parameters: absolute plate velocity of the site, minimum distance between neighboring hot spots, minimum distance from a ridge, minimum distance from a trench, geoid anomaly of harmonic degrees 2--10 and 11--36, area of the host plate, lithospheric thickness, and stress state. The hot spots, generally defined as volcanoes not obviously related to plate boundaries, are found to occur in sites characterized by either one of the two main significant patterns: (1) positive values of geoid anomalies with harmonic degree between 2 and 10, which is characteristic of most of the hot spots with a ''track'' of extinct volcanoes; (2) clustered volcanoes (distance between volcanoes less than ~900 km) in slow moving plates (velocity ≤2.5 cm/yr). A third pattern, representative of isolated volcanoes (distance between volcanoes greater than ~900 km) anomalously close to mid-ocean ridges (distance from the ridge less than ~600 km) can also be tentatively identified. This result implies the existence of two main types of hot spot volcanism, the first one of sublithospheric origin with dynamics which is not influenced by surface tectonics, and the second one mainly due to a favorably ''soft'' lithosphere. A third type would probably consist of ''anomalous'' and magmatically very productive parts of mid-ocean ridges. ¿ American Geophysical Union 1993