Well then, let me give you the quick and dirty on it:
The AoE games are RTS games, set amidst actual historical events. Probably the biggest competitor of Sid Meier's Civilization series.
Your job is to start up civilization and lead it through the major advancements, specifically from the Dark Age through the Imperial Age (think Renaissance)- a thousand year timeframe give or take. Later games added more civilizations and other perks to the existing gameset. The civilization you choose to start (will determine what special technologies you get to unlock as you advance through the ages...the epitome of which is the Wonder. It takes a lot of resources (both human and arable, not to mention wood, stone and gold) to build and can be easily destroyed before it reaches completion. Once it does so, however, it is quite difficult to bring down, and each civilization has their own unique wonder that can only be built of certain parameters are met (generally speaking, you will have to have leveled your civilization to its zenith before you can begin).
I literally spent hundreds of hours planning and building my towns, building walls to protect said towns, planning out farming regions, housing and consumables...not to mention the number of warrior units you could train, but only if you've upgraded your barracks and equestrian (and later siege shops) centers to accomodate the newer tactics. All in all, a great franchise...and excellent background music as well.