Merging table cells combines adjacent cells into one, eliminating the borders so that they behave as a single cell.
Select a group of two or more adjacent table cells. The group of cells you choose must form a rectangle, and they must be all body cells, all header cells, or all footer cells.
Do either of the following:
Choose Format > Table > Merge Cells.
Click Inspector in the toolbar and click the Table inspector button. Click Table in the Table inspector, and then choose Merge Cells from the Edit Rows & Columns pop-up menu.
Choose Format > Table > and deselect Merge Cells.
Deselect Merge Cells in the Edit Rows & Columns pop-up menu in the Table pane of the Table inspector.
Here is what happens to cell content when you merge cells:
Merging horizontally contiguous cells containing only text or a mixture of text, numbers, formatted values, and formulas joins the content from all the original cells as text separated by tabs.
Merging vertically contiguous cells containing only text or a mixture of text, numbers, formatted values, and formulas joins the content from all the cells as text separated by carriage returns.
When you merge column cells, the cell background takes on the image or color that was in the topmost cell.
When you merge row cells, the cell background takes on the image or color that was in the leftmost cell.
When a cell containing text, a number, a formula, or a cell format is merged with an empty cell, the new cell retains the content of the non-empty cell.
When a cell containing a number format is merged with an empty cell, the new cell retains the number format.
For detailed information about how to use the hundreds of iWork functions, choose Help > Formulas and Functions Help, or go to Formulas and Functions Help on the web.