In early console RPGs, such as Dragon Warrior, players were dependent on inns to fully restore the party's health and (more importantly) magic. The original Final Fantasy introduced tents; consumable, one-use items that acted as portable inns, fully restoring the party in the field. Later Final Fantasy games reduced the healing power of tents and introduced cabins as a more powerful version.
Tents have since been widely adopted in (Japanese) RPGs, with their exact functionality (reviving fallen characters, healing status aliments, allowing players to save) varying between games, but typically offer the same restoring power as a visit to an inn.
Use of a tent is restricted to the field map or in other safe area, limiting their usefulness in deep dungeons. Tents usually cost much more than a stay at an inn, but less (per point restored) than a combination of healing and mana restoring potions.
More recent games have provided reasons for the consumable nature of tents. In Tales of Vesperia for example, each tent comes with a temporary anti-monster scent, while in other games the tents provide temporary magical protection.