When you are typing data into a list, Microsoft Excel will attempt to guess what you intend to type based on the data in the cells above the one in which you are typing. The example below illustrates this. Only the letter "B" has been typed into cell A4. Excel is guessing that the user intends to type "Ball":
If the user does intend to enter "Ball", he or she can press Enter as soon as Excel has correctly guessed.
Things to be aware or regarding the AutoComplete feature: