What is the 'Task List' and what is its importance to the workflow designed in SharePoint 2007? Can 'Task List' be considered to be a substitute for workflow?
When a workflow expects an action from a user, this action is assigned to a specific person or group as a task ( = item in the task list). When you design the workflow you can define this person or group as receiver of the task.
Example: if you have a workflow for a holiday request, the supervisor must confirm the holiday requests of his subordinates. This is assigned to him as a task via the task list.
The task list provides several views by default and you can define further custom views, for example that you can see only your own tasks or tasks that has been assigned to your group.
Therefore you can consider the task list as a necessary part of each workflow that requires a user action but not as a substitute of a workflow.
Have a look on the several topics in this link: http://office.microsoft.com/en-us/sharepoint-designer-help/results.aspx?qu=collect+data+from+a+user+in+a+workflow&ex=1&origin=HA010209808
From my understanding the Task List holds the list of task that are to be handled when a particular task is assigned to any person. The Task List is Important for the workflow but could not be considered as the substitute for the workflow itself.
For better understanding of the Task List just try to work on it and refer this following links. Hope it helps.