Minecraft mods are modifications that help in making the minecraft experience better. These are generally developed by third parties (not Mojang AB). Among the many mods available today, Bukkit is the most popular. It is easy to install and offers a platform for implementing a large variety of modifications. Plus, it is highly customizable too. Not just for the gamers, but also for the plug-in developers, Bukkit is an interface for easy integration of plugins.
Basically, Bukkit is a developer API (Application Programming Interface). In simple terms, say, a developer wants to add some new feature to Minecraft. It could either be a game feature or an admin (management) feature. For doing so, he might have to alter the code or add his own code to the existing minecraft server code. Now, with so many developers out there, each of them wanting to add their own modification, it would make the minecraft server bulky and messy. This is where mods like Bukkit save the day. Bukkit forms a layer or an interface between the minecraft server and the modifications. The developers can use the API functions offered by Bukkit to form their plug-ins or modifications. These plug-ins can then be easily plugged into the minecraft server, without actually having to alter the minecraft server code. This keeps the server clean. The plug-ins can as well be removed easily when not required.
The component of Bukkit that is installed on the server, is called CraftBukkit. It is in fact a Minecraft server, which can includes the Bukkit component. The plug-in developers can use the standalone Bukkit API to create and test their plug-ins.
Installing and setting up Bukkit and the plug-ins is very simple. You can find the detailed steps for Windows, Mac OS X and Linux at the Bukkit Wiki – Setting up a server.
Alternatively, you can check the newbie-friendly installation.
After installing CraftBukkit, here’s what you do for using plug-ins on Windows:-
1) Visit the Bukkit Forum.
2) Click on Plugin Releases on the page. This will give a long list of plug-ins. Choose the one you want. Clicking on the plugin will give you all its details and the download link as well. Ensure you read the instructions carefully and do as necessary.
3) In case you haven’t already run your CraftBukkit jar file (atleast once), then do so, by running the .bat file that you previously created. After it initializes completely, stop it, by typing stop at the console. This step is done, just to create the necessary files and folders. A folder called plugins would have also been created now. Place the plugin jar file (and other folders if needed, as per the instructions) that you downloaded inside this folder.
4) You can then run the .bat file to start your server. You will most probably get a message on the console, that the plugin was initialized/enabled/loaded successfully. Some plugins have a config file, which can be edited to make configuration changes as per your requirements.
YouTube video for installation of CraftBukkit on Mac OS X.
YouTube video for installing Bukkit plugins on Mac OS X.
Setting up a CraftBukkit CentOS Server.
YouTube video on setting up a CraftBukkit Ubuntu/Debian Linux Server, along with plug-ins.