Final answer:
The Tab key is used to move the cursor from field to field within a record when navigating a main form.
Step-by-step explanation:
When navigating a main form, pressing the Tab key will move the cursor from field to field within a record. The Tab key serves as a navigation tool in many software applications to move from one input field to another. Pressing Shift + Tab will typically move the cursor to the previous field, which is useful for navigating backwards through the form.