Editing Civilization IV (section)

===Technology, government and religion===
[[File:Civilization4-Civics.jpg|thumb|upright|A screenshot of [[government|Civics]] option menu in ''Civilization IV''<ref name="cavgames"/>]]
Once the first city has been founded, the player can select their first technology node from the game's technology tree to research, once the required number of research points have been accumulated, the technology is obtained. As with other types of technology trees, more advanced technology nodes require the research of other previous technology nodes.  The player can also select a future technology and immediately place into the game queue any technology nodes between the current technology level and the specified technology node. Technology can also determine another win condition; several endgame technology nodes are required to develop a colony ship to reach Alpha Centauri.<ref name="ignreview"/>

Within the technology tree are technology nodes relating to government civics and state religions, each with their own pros and cons. The player has the option of selecting which set of government civics or state religions that the player wants their civilization to follow, but not all civics and religions can be encompassed.

Once the player has formally met another civilization, they can perform diplomacy at any time. For example, if the two civilizations are on friendly terms, the player can ask to trade units and/or technology for gold and vice versa, or request opening of national borders in order to freely explore in the other civilization's territories. The player can also use the diplomacy menu to request help in a war against a third civilization, or formally declare war on any civilization in which they engage diplomacy.

Religion plays a much more important role in ''Civilization IV'' than in the previous installments of the franchise. Impacting many of the game's key mechanics like government civics and diplomatic relations, the game's new religious system, according to [[Firaxis Games]] producer Barry Caudill, was added to increase gameplay depth over the entire game.<ref>{{cite web|url=http://www.gamespot.com/articles/religion-demystified-in-civilization-iv/1100-6129610/|title=Religion demystified in Civilization IV|first=Andrew|last=Park|date=22 July 2005|website=gamespot.com|access-date=9 May 2018|url-status=live|archive-url=https://web.archive.org/web/20160727082624/http://www.gamespot.com/articles/religion-demystified-in-civilization-iv/1100-6129610/|archive-date=27 July 2016}}</ref> The game features seven religions (Buddhism, Christianity, Confucianism, Hinduism, Islam, Judaism, and Taoism) that are founded by the first civilization to research a certain technology which varies per religion. Religions can then be spread actively through the production of missionary units or passively through means such as trade routes. Religions may be spread to domestic and foreign cities and there is no limit to the number of religions that can be present in any single city. The player may only choose one state religion at a time and all seven offer identical advantages (e.g. cities with the state religion receive bonuses in happiness, and potentially in production, science, gold and even military unit experience points).