SharePoint Lists are the real building blocks of any SharePoint Solution. All walks of SharePoint life, whether they are a Developer, End User, Power User or Administrator will utilise Lists and their collection of List Item children.
Common examples of Lists are:
Document Libraries storing Word Documents
Page Libraries storing Pages in a Publishing Portal
Tasks Libraries storing Tasks in a Workspace
End Users
End Users will access the Lists via the Site Web UI. Information shown on pages, such as Recent News may be just consumed within a Web Part on their Home Page. Power Users may be adding new News to the News List in the background and the Users don't have any knowledge of where these lists are.
Power Users
Power Users will access the Lists via the Site Web UI and also via SharePoint Designer. As mentioned above, Power Users may be adding new News Articles via SharePoint Designer into the News List.
Developers
Developers will access the SharePoint Lists programmatically using the SharePoint Object Model. Developers may be tasked with accessing the News Items as they are created and automatically triggering a Workflow process.
Administrators will back up the Content Databases where the Lists are stored and possibly have to restore individual List Items using third party tools or by manipulating the Recycle Bin.