An era is a period of time in Civilization V and its expansions. Civilizations can progress to a new era either by researching all technologies from the current era, or by researching one technology from the next era. In Civilization V: Brave New World, the World Congress progresses through the eras as well, advancing when at least half the civilizations in play reach a new era or one civilization reaches the era beyond it. The eras in vanilla Civilization V are as follows: In Civilization V: Gods & Kings, the Future Era is removed and replaced by two new eras: