A cell address is simply the combination of the column letter and the row number for the cell being referenced, without a space between them. As previously stated, the cell address for the top left most cell for any worksheet is A1 because it is in the first column and the first row. The address for the cell in the 26th column and the 9th row would be Z9. You can always know which cell you have selected (the cell with the bold outline on it) by using the always visible column and row labels to infer it yourself or by observing the selected cell address box just above the A1 cell.