Auta fill can only be used to continue a sequence of numeric data and will not work on qualitative data such as months of the year or days of the week.

Auto fill can only produce a sequence or copy and paste data and cannot be used to only paste the formatting of a cell to other cell locations.

Auto fill can be used to continue a sequence for the months of the year, but the months must be completely spelled out and cannot be abbreviated.

To delete data in the bottom $5$ rows of a column, highlight the column and then click and drag the Fill Handle up $5$ rows.

When two or more cells are highlighted, auto fill can only be used to complete a sequence and cannot be used to duplicate the data in the two cells.