Whereas in theory members of the Roman Senate and their sons were restricted when engaging in trade, the members of the Equestrian order were involved in businesses, despite their upper class values that laid the emphasis on military pursuits and leisure activities. Plebeians and freedmen held shop or manned stalls at markets, while vast quantities of slaves did most of the hard work. The slaves were themselves also the subject of commercial transactions. Probably due to their high proportion in society (compared to that in Classical Greece), and the reality of runaways; as well as, the Servile Wars and minor uprisings, they gave a distinct flavor to Roman commerce.
The intricate, complex, and extensive accounting of Roman trade was conducted with counting boards and the Roman abacus. The abacus, using Roman numerals, was ideally suited to the counting of Roman currency and tallying of Roman measures.
The Romans knew two types of businessmen, the negotiatores and the mercatores. The negotiatores were in part bankers because they lent money on interest. They also bought and sold staples in bulk or did commerce in wholesale quantities of goods. In some instances the argentarii are considered as a subset of the negotiatores and in others as a group apart. The argentarii acted as agents in public or private auctions, kept deposits of money for individuals, cashed cheques (prescriptiones) and served as moneychangers. They kept strict books, or tabulae, which were considered as legal proof by the courts. The argentarii sometimes did the same kind of work as the mensarii, who were public bankers appointed by the state. The mercatores were usually plebeians or freedmen. They were present in all the open-air markets or covered shops, manning stalls or hawking goods by the side of the road. They were also present near Roman military camps during campaigns, where they sold food and clothing to the soldiers and paid cash for any booty coming from military activities.
There is some information on the economy of Roman Palestine from Jewish sources of around the 3rd century AD. Itinerant pedlars (rochel) took spices and perfumes to the rural population. This suggests that the economic benefits of the Empire did reach, at least, the upper levels of the peasantry.
The Forum Cuppedinis in ancient Rome was a market which offered general goods. At least four other large markets specialized in specific goods such as cattle, wine, fish and herbs and vegetables, but the Roman Forum drew the bulk of the traffic. All new cities, like Timgad, were laid out according to an orthogonal grid plan which facilitated transportation and commerce. The cities were connected by good roads. Navigable rivers were extensively used and some canals were dug but neither leave such clear archaeology as roads and consequently they tend to be underestimated. Maintaining peace was a major factor in the expansion of trade. All settlements, especially the smaller ones, could be located in economically rational positions. Before and after the Roman Empire, hilltop defensive positions were preferred for small settlements and piracy made coastal settlement particularly hazardous for all but the largest cities.