This question can be too ambiguous but i think many new drupal users face this difficulty like me.
There are many blogs which says that Drupal is a CMF and we can use it for making Web Application rather then using it like Wordpress for articles and pages.
For the sake of example lets say i have to make a task management system with a specific Application style UI and features. If i would have to make it by custom programming i would be making tables for tasks, users, task_attachments, clients and so on and will make relations accordingy.
My question is how we can do all this stuff in Drupal? Nodes are for content and i would not go for nodes to achieve this. The other thing is Entity but How one can properly utilize Entities. If i have to list all tasks for a specific user, If a user want to update a status of his task or attach some file, If its a team and other team members should also be allowd to post updates on tasks. These are the common application scenarios that we usually make in this kind of application.
If someone provide a brief workflow then it would be a great effort for helping beginners like me to use Drupal as a developer rather than doing a data entry job by installing modules and copying content , images.
There is a good example erpal.info but its too advanced for me at this level to jump into it. but a mini erpal would be great.