Vendors selling prepared food are as old as civilization itself. As far back as the Ancient Egyptians and Romans, simple food stands existed where you could buy cooked meat or stews. Most people in the major cities of the Roman Empire lacked cooking facilities (beyond a charcoal brazier that could easily burn down the block) and would instead frequent the popina, thermopolium, or taberna. The exact differences between these are not solidly defined, but all of them sold drinks and some form of food. Smaller wine bars would just sell bar snacks like salted chickpeas, while the more serious establishments would have stews, smoking sausages, and boiled meat dishes. As found in Pompeii, they often had a U or L-shaped low bar with pots set inside the bar to insulate the contents, which could be scooped into a bowl.

This practice continued in medieval Europe for the most part. Urban areas always had more food vendors than others, but there's still no "restaurants." You could pick up meat pies, bread and cheese, sausages, or salt cod at a street stall but taverns/inns were generally only frequented by travelers passing through. Exactly what they had depended on the day and what was available, and the proprietor would give you a price that you may be able to haggle. There were no menus.

The first record of a restaurant as we know it actually comes from Song Dynasty China, in the time of Marco Polo's visit. Restaurants were described as having dozens or hundreds of dishes. The following account is from 1275 in Hangzhou:

“As soon as the customers have chosen where they will sit, they are asked what they want to have. The people of Hangchow are very difficult to please. Hundreds of orders are given on all sides: this person wants something hot, another something cold, a third something tepid, a fourth something chilled; one wants cooked food, another raw, another chooses roast, another grilled…..”

It would be over 400 years before this format would appear in Europe, with the very word "restaurant" coming from France.

In the 18th century, "restaurant" literally meant "something that restores." It referred to meat broths, which were viewed as a rejuvenating and energizing dish. At this time, the French food industry was dominated by guilds who kept everything strictly confined to guild membership. You went to a patisserie for pastries, a charcutier for prepared and preserved meat products, a rotisseur for roasted meats, etc. Cook-caterers, or traiteurs, had shops where occasionally one could buy food and sit down to eat inside, but mostly sold their services to wealthy clients looking for multi-course meals.

Restaurants were legally restricted to selling bouillon, though they would incorporate all sorts of meats, vegetables, and herbs and spices into the otherwise simple dishes. They were also distinguished from the other shops and the traiteurs by selling individual dishes, rather than ingredients or items meant to be combined into meals.

Around 1765, a Parisian restauranter named A. Boulanger attracted the ire of the guilds by selling sheep's feet in a white sauce, which was not a restorative broth. While the courts found in favor of the traiteurs, one effect of the French Revolution was the abolishment of the guild system with the Le Chapelier Law of 1791. This opened the market for restaurants, cafes, bistros, etc. to come into existence and eventually spread worldwide.