SQL Server comes with a standard configuration which autogrows data files in databases in 1 MB increments. By incrementing in such small chunks, you risk ending up with a very fragmented data file on your disk. Consider a 200 GB database which have grown to its size by 200.000 auto grow events. In that case you might end up with a data file in over 200.000 fragments spread all over your disk.
To avoid getting a higly fragmented data file, we recommend that you always change this value on every new database you create, and also existing databases which still have the 1 MB autogrow configured.