Automatically route newly added records to the appropriate assignee using a variety of workflow options.
Route Automatically for All Users
When the Assigned To field is not visible on the Add Page, the new record is assigned to the State Manager. A State Manager is a role where you can select a specific user to be responsible for the records routed to a particular state (step) in the workflow. The Online Help Guide has examples of how state managers can be configured.
Route Automatically for Most Users
You might have a set of users who need to be able to pick who should be assigned to the record (e.g. Managers or users who handle special cases). You can show the Assignee field to those users, but hide it from everyone else. This is done using the Field Visibility feature.
The Administration Help Guide provides a full description about how automatic assignment works.