Different types of mosaic appear in Roman times where at the same time artists specialize in a particular skill. So, we can see the pictor imaginarius, who paints the different subjects, the pictor parietarius, who transfers the painting from the cartoon to the surface which is to be decorated by the musivarius (for walls and ceilings) or the tesselarius (for floors) with the tesserae. We give here some names of artists who signed their work; some are Greek, others are Roman but their works spread worldwide; Amitaion, Amiteius Quintus, Antaios, Anthos, Apollinaris, Asklepiades, Blastos, Cecilianus, Dioskourides and others. The materials used for mosaics are: pebbles, natural rocks cut to cubic tesserae, enamel tesserae, gold-glass tesserae. As binding materials were used: lime, pumice, marble and ceramic dust (sometimes egg was added). At the end of the 19th c. portland cement is widely used.