If you begin typing an entry and then realize that you don't want your entry placed into a cell, press Esc or click the Formula bar's Cancel button.

When you want to change a cell's information, you have two choices. You can replace the cell's existing contents by typing over them. For example, you can click the cell, type your new entry, and press Enter. Or you can edit the existing entry.

To edit a cell's contents, double-click the cell. Excel turns the cell into an editable text box. You can then edit the cell's contents in the same manner that you edit the contents of any text box. To place the edited cell contents back into the cell, press Enter or click the Formula bar's Enter button. To erase the contents of a cell, select the cell and press the Delete key.

TIP: You can't erase the cell data by clicking on a cell and pressing the Spacebar. While this technique appears to work, it really doesn't because all you're really doing is replacing the cell's current contents with a space character. This can cause problems later if the cell is included in calculations.