There are several resources which are important when playing Fallen Enchantress. Some examples are Gildar, Influence, Prestige and Mana.
This is the gold in the world of Elemental. Used for buying items for your heroes, speeding up construction once you have the appropriate tech, and used for recruiting new heroes or bribing other players in diplomacy.
Influence grants you the respect of your opponents, as well as the allegiance of some neutral creatures. When you have a lot, they will like you more, be less likely to attack you, and you will get better deals from them. You can also trade influence away, or you can try to buy it for resources, but neither is recommended. Losing influence can lead to your friends turning on you, and purchasing influence is insanely expensive. Some races have specific uses for influence: some can recruit monsters as allies, Altar can train sidekicks, Kraxis can charm cities and units away from their original side. Influence can be gained by exploiting prestigious locations, constructing specific city buildings, declining other rewards from quests, etc...
Research is a measure of the ease with which you master new technologies. It is generated by some heroes, city buildings and enchantments. It can be increased with technology treaties with other nations, and it can be even found and traded. You usually set a research target, and most acquired research goes towards that target. There are exceptions.
Prestige attracts people to your cities, providing a bonus to their Growth. Prestige is also needed when making certain units, which need a minimum prestige amount to be trainable. Prestige is shown next to the chalice icon at the top of the screen.
Prestige bonus to growth seems to be a simple formula of Prestige / # of Cities = Growth (for all cities). Small empires will grow fast, while large sprawling empires will grow slower.
Mana is a global resource for spell casting in your faction. Any time a unit or hero uses a spell in the tactical or strategic view, this resource is expended. All spell-casters share this resource. The amount of Mana generated each turn is determined by Cities and Heroes in your control. Cities can get more Mana by building certain improvements, having enchantments cast on them and the number of essences attributed to the city. The best way to generate more Mana is to control more elemental shards, and upgrading them. A Mana rich faction will be able to cast more spells to aid in combat, as well as economically and strategically.
This resource can be attained by building an improvement on Wild Horses tiles. It is used when creating units that use a Horse. It is not needed when purchasing a horse for hero units.
Same as horses, must find wargs tile and build improvement on it. Will provide armies with Wargs to ride. Wargs are provide better melee defense than Horses, but are slower and do not add weight capacity.
Metal is needed when creating units that use metal weapons and armour. It can be found in Iron Mines, which must be improved upon.
Crystal is a resource primarily needed for magical equipment and improvements. Units using this equipment will cost a certain amount of crystal.
Each time you discover a new technology, a portion of the research cost of that technology is saved as Knowledge. The type of Knowledge is that of the tree that technology falls under. Knowledge can be traded between players. When receiving Knowledge from another player, it is instantly applied as Research towards technology in the appropriate tree. Only Knowledge received from another player can be converted to Research. (Not to be confused with the Knowledge technology, which is unrelated.)
 City Resources
For city-level resources such as Grain, Materials, Essence, Production, Food, Population, Growth, and Unrest, see City Resources.