Continuation of this post.
As every TiddlyWiki, the main building block of the MGTDTW (MonkeyGTD TiddlyWiki, if you are wondering what kind of monstrous acronym is that) is a tiddler. And the only one building block because everything is a tiddler. How does this map to the GTD approach ?
The GTD workflow works with projects, contexts and actions. Action (or task or todo) is smallest building stone. The actions in GTD are really small actions. Every goal that requires multiple steps is a project - thus project has multiple actions. Context is an environment for executing the actions - e.g. Office, On-Line, Errands. Action can be in of the the state: "next" - ready to be started, waiting-for (something else needs to happen before you can start), future (something you may want to do later but not really a task right now) or done. OK, this is slightly oversimplified - for real explanation check the resources in Part I.
Everything GTD related in MGTDTW is done using tags on tiddler and "special tiddlers". Because tiddlers are all there is, all your actions are tiddlers. So are all your projects and context. What makes "action tiddler" differrent from "project tiddler" is that action tiddler has tag "Action" and tiddler representing the project has tag "Project". The Wiki is smart enough to provide an easy UI to assign the tags and to create the tiddler. For example, inside the "project tiddler", you have links to add new next action, new waiting action, new future action. Each of this create new tiddler, tags it with "Action" tag as well as with appropriate action status tag.
Some tags have graphical representation rather than verbal. Clicking on yellow start will assign/unassign the tiddler Starred tag. Starred items are quick reference list for wide variety of the usage.
If you read The Book, you will learn about other concepts such as reference file and ticklers. Good news is that the MGTDTW implements both. The tickler is special UI for the tiddler connected with the year-month-day - an activation date. The reference is simply a tidller tagged as Reference. Simply use subject matter tagging in addition to that to properly categorize it. But whether you tag it or not, you can always find it using fulltext search as well as see it in the timeline
The MGTDTW has also few extensions above the "canonical" Allen-ist GTD (if such thing as cannonical GTD exists at all). These extensions are Areas - something similar than projects and Realms - something even wider. By default, two realms are defined: personal and work, which pretty give an idea how they can be used: separate world or zones of responsibilities. The areas are trickier: they can be used as groups for projects (for the control freaks ;-)). The UI design of the project suggest this usage and makes it very easy. In one of the Mac programs (I believe it was Things) I have founds different explanation for area: it is kind of project that is never done - like house maintenance. MGTDTW does not directly support this semantics, because the action UI does not offer the Area, only Project. But nothing prevents you in the edit mode tag the action with the area tag. It will show properly in the Area view as the Next Action, even if it is not assigned to a project.
Many of these concepts are actually much easier to see and experience than explain. So why not donwload the MGTDTW and play with it ?