Spring is in the air. The buds are blooming, the birds are singing, and the crack of the bat at the ballyard means one thing to computer users everywhere: fantasy baseball.

Millions play the national computer pastime, but things have changed since the days of the pencil and paper at the Rotisserie Baseball league. In fact, things have changed since two years ago. Major League Baseball has asserted its exclusive rights to the statistics generated from Major League Baseball games. This means that you have to pay a license fee to run a fantasy baseball service. It also means that even if you have the money, MLB can say no.

Still, if you just want to play in a league or better yet, run your own league, you have lots of choices. Here's my spring training guide to some of the variations you have to choose from and what to expect from the major services. So how do you get in the game?

Single player
The easiest way to play is join a free public league. These are leagues that allow anyone to sign up and place you in a league with other people, most likely people you don't know. These leagues are easy and often organized by difficulty level. They tend to be less interactive. People fear trading with people they don't know. They'll also be more prone to oddball players who either play below their level or do ridiculous things, such as dump quality players during the pennant race.

Play with friends
Another way to play is to join a private league. These usually run the same way as the public leagues, but members have to be invited. To be invited, you either get in with a friend or start your own league.

Run a league
If you're really ambitious, you can start your own league. Nothing is more fun, in my opinion. League management tools range from the very simple private league of a Yahoo to the full commissioner management tools of a CBS SportsLine.

What type of game should I play?
No matter which kind of league you join, you'll also have to choose which variation of fantasy to play. The three main kinds are the classic Rotisserie, points-based, and head-to-head.

Rotisserie league baseball is the legendary game started way back when the Internet was command line only. With Rotisserie, you choose players and you get ranked based on particular stat categories. So, if, say, home runs is a category, every home run your players hit helps your home-run ranking. Rankings for all the categories combine to create your overall ranking.

Points-based is sort of a spin-off of Rotisserie. In this game, every stat accumulated scores a certain amount of points. The total points can determine your ranking, or you can play against another team. The squad with the most points in each period gets a win.

The style called head-to-head pits teams against each other, usually each week. A certain amount of stat categories each count for a point. The team with the better stats in that category gets a win. The standings reflect the win percentage of teams.

Should I pay or not?
There are plenty of free services that are perfectly adequate for the casual fan. If you don't want to spend every minute checking scores and agonizing over whether Craig Counsell will get enough bats to up your steals, just play for free. However, if you want to run a fun successful league or you want serious competition, consider paying.

Will I get addicted?
You might. Be careful.

Running your own league
I operate a league, so I'm going to run down the major options you have in running or playing in a fantasy league. There are also many other options for playing games that win you money or don't even involve picking a team.

CBS SportsLine
This is the service I use to run my league. It offers a product called Baseball Commissioner, which is the continued development of the old commissioner.com. I like it because it allows a lot of customization that others don't, and it has a cool feature that lets league members post stories to a league home page. We play a head-to head league, and it feels sometimes like the Commissioner product was built more for Rotisserie. Sometimes it takes a few clicks to get what you want done. It also doesn't show dynamic player rankings among free agents. You just have to read the stats and make your own decisions. That's a little harder for newbies.

SportsLine also offers a free fantasy baseball product. It's not very customizable, but it does allow you to join a public league or create a private one.

The Sporting News & MLB.com
Major League Baseball uses the Sporting News to operate its fantasy league option, called Draft and Trade. You can purchase up to five teams in public leagues or purchase your own league. The leagues are fairly customizable, offering head-to-head, Rotisserie, and cumulative (points-based) options. I love the quality of information you get from the Sporting News, but it doesn't allow total customization of the head-to-head leagues. It gives you three preset options to choose from. If you don't care to experiment with Home Runs Against or Holds in your league, you may not care about that.

Yahoo
Yahoo has the best free service, in my opinion. I ran my league through Yahoo until we outgrew the options. I almost always end up in a Yahoo league each year, one way or another. It has the best integration of stats and player rankings I've seen yet. The user interface is also pretty easy to catch on to.

ESPN
I have never played an ESPN fantasy product, nor do I know anyone who has. However, millions do. ESPN doesn't offer a total commissioner-controlled private league option. However, it offers prizes in all its leagues. You can buy up to five teams or join a three-year keeper league.

National fantasy baseball championship
The National fantasy baseball championship is a contest sponsored by Major League Baseball and aims to determine the best fantasy players.

CDM Fantasy Sports
These are the main guys fighting MLB over the rights to run a fantasy baseball service based on Major League stats. It seems like most of its offerings are also contests with prizes, much like ESPN. It does list one called TQ Stats that I believe may have been a separate operation at one point. TQ Stats will actually run your league for you, so that one of the teams doesn't have the conflict of interest of being the commissioner. But it's totally customizable.

These are just the big companies that I'm familiar with. You can also find lots of smaller operations out there that may suit your needs more particularly. You can find a comprehensive listing of services at the Open Directory Project.