A task is a concrete step that’s required to meet a project goal. It represents actual work that will be done in your project, the underlying structure of your project.
To manage your project effectively, you need to define your tasks so that they are the right size. If your tasks are too large, they might mask smaller tasks that actually need to be completed and tracked separately. If your tasks are too small, they might be trivial and clutter your project plan, making it difficult for you to manage the tasks that are truly critical to your project.
For example, laying a tower foundation is too large to be one task. Why? Because there really is no single task "Laying the tower foundation." It’s not a single action that can be done all at once. To accomplish this goal, various tasks such as digging a hole and pouring concrete must be performed. These are the tasks that would be included in a project plan. (Though "Laying the tower foundation" could be considered a summary task that includes the other tasks; see "A Logical, Well-Ordered Task List" later in this chapter.)
On the other hand, an action such as turning on the cement mixer is too small to be included as a task. By itself, it doesn’t advance the project at all. It’s really part of the task of pouring the concrete.
The main thing to remember is that although tasks should be well-defined, precise, and detailed, they must also be significant. Their completion should move the project forward measurably.