What is the tab key primarily used for in document formatting?

The tab key is primarily used in document formatting to create an automatic indent. When the tab key is pressed, the cursor moves to a predefined position, which helps in aligning text consistently and creating structured documents. This feature is especially useful in lists, outlines, and paragraphs where uniform indentation is necessary for clarity and organization. The tab function streamlines the formatting process, allowing users to maintain clean and tidy layouts without manually adjusting each line's position.

In contrast, other options do not accurately reflect the primary use of the tab key: deleting text involves different keys, line spacing relates to specific formatting settings, and switching between applications typically requires the use of keyboard shortcuts or command keys distinct from the tab key.