Feature that fills cells automatically based on pattern:

The feature that automatically fills cells based on a recognized pattern is AutoFill. This is commonly used by dragging the fill handle (the small square at the bottom-right corner of a selected cell or range) to extend a series of numbers, dates, or custom lists.

• AutoComplete helps complete text entries in a column based on existing entries, preventing retyping, but it doesn't fill a series of cells.
• AutoCorrect automatically corrects common typing errors or replaces specific text strings as you type.
• Flash Fill (introduced in Excel 2013) is a more advanced feature that intelligently parses and combines data based on patterns, often used for splitting or joining text, but AutoFill is the foundational feature for extending patterns in adjacent cells.