Before a restaurant was a place, it was a bowl of soup.
The French verb restaurer meant "to repair, refresh, renew," and its present participle, restaurant, meant "restoring." Etymonline says the word was first applied to food that restores. In practice the food was a strong broth or consommé, sold as a restorative to customers who wanted small portions of simple food for their health.
A famous story names the man who started it all. A soup seller called Boulanger supposedly opened the first restaurant in Paris around 1765 on the Rue des Poulies. Etymonline traces the earliest account to a 1782 description by Le Grand d'Aussy, who writes that he sold broths and consommés from a shop on the Rue des Poulies.
The legend grew from there. Larousse Gastronomique credits Boulanger with the first modern restaurant. The tale adds a sign promising divine restoratives and a lawsuit by rival caterers, the traiteurs, over sheep's feet in white sauce. National Geographic reports that the historian Rebecca Spang found no trace of Boulanger or the case in French archives. Absence from the archives does not prove he never existed.
Other names compete. Etymonline says that before the 1780s other accounts named Duchêne, Roze or Vacossin as the first restaurateur. Spang's research points to Mathurin Roze de Chantoiseau, who called himself the creator of restaurants. Another historian, Ken Albala, thinks the Boulanger story may hold some truth but declines to name a single "first."
Larousse credits the Grande Taverne de Londres, opened in 1782, as the first Parisian restaurant worthy of the name. National Geographic describes a "Restaurant Revolution" after the French Revolution, when private chefs lost their aristocratic employers and a new middle class could eat out. Spang finds little evidence that the Revolution itself created restaurants. In her account they were already under way before it and spread widely after 1794.
English adopted the word early in the 19th century. Etymonline puts the first English use at 1806, in the sense of an eating house where meals can be bought. It arrived as a French word and stayed.