Age of Empires is a series of games that were created by Ensemble Studios starting in 1997 with the first game. It's a real time strategy game that focuses on gathering resources (food, wood, gold, etc.) and developing a village and army to eventually overtake your enemy or enemies and win the game. It features different civilizations that have their own buildings, units, etc.
The first one came out in 1997. It's probably the least played since the previous games have come out. Personally I haven't played a lot of this one, but it's still fun if you can find a copy somewhere. It features civilizations such as Egyptians, Greeks, Babylonians, and more. In 1998 it got the expansion The Rise of Rome which added some new units and a whole new musical score as well as some tweaks but besides that it didn't add too much.
The second AoE, or age of kings is considered the best in the series by many and still played online today. It came out in 1999 and is still freaking awesome. It later got an expansion known as the Conquerors.http://www.youtube.com/watch?v=pKxWHEiuIbI
It's also educational and is a good excuse to learn history with campaigns following people like Joan of Arc and Ghengis Kahn.
Oh, and one of the reasons why I made this thread is it because there is a good possibility it's coming to steam! With achievements!http://www.reddit.com/r/Games/comments/19fboa/age_of_empires_2_very_likely_coming_to_steam/
Also a new unofficial expansion called the forgotten empires just came out a couple months ago! I haven't tried it yet, but it adds more resolutions and new civs. It's supposedly pretty good.
If you can't wait for the steam release it's not hard to find the gold edition for 10 bucks at places like Walmart or Office Max.
In 2005 we got AoE3. Personally, I enjoy it, but I know a lot of people aren't fond of it. But it did add some new stuff and actually got 2 expansions that added native American tribes and Asian civilizations. The complete edition is on steam for 40 bucks, which is still a little pricey. So unless you're dying to play it now, I'd wait for an inevitable steam sale when it'll most likely be like 5 dollars. It actually ended up being my greatest game deal ever when I got it from games for windows on sale for a few MS points, which in USD was literally about 10 cents. Sadly, this would be Ensemble Studio's last AoE game and next to last game period before it closed it's doors in 2009.
The newest AoE was made by robot entertainment, which was founded by some former Ensemble guys. It's really cartoony and looks a lot different than previous AoE games. It's also more of a MMO game and is free to play. Its...ok. Unless you're broke and don't have access to any other AoE game, I wouldn't recommend it. I've also heard nothing new is being made for it, and like most MMO and f2p games, it's full of morons. So yeah.
There have also been some spinoff AoE games such as Age of Mythology, which I don't know a lot about, but feel free to talk about them here too because I've heard some of them are excellent as well. Here's hoping that MS who still holds the rights to AoE has someone working on an AoE4.