If you save a file with a name that ends with a period — for example, "Sales." — Microsoft Office programs add another period and the program file extension to the file name. So if you typed the presentation file name as "AnnualSales.", it is saved as "AnnualSales..ppt".

While this isn't harmful, some people think it looks funny and it can be confusing if you have links.

To prevent this, when you save a file, do not type a period following the file name. If you have already saved the file, you can rename the file.

Note  In Microsoft Windows, file names can contain some punctuation characters, such as commas or periods.