The important thing to remember about an asterisk is simply that it points to something else. It does not convey an idea on its own. The use is not to emphasize or to stress something. Essentially, it is a pointer to a footnote at the bottom of a page that serves to elucidate or to provide an exception or limitation to something in the text. It is similar to a numbered footnote but is usually used when there are only a few notes on a page.
Properly use an Asterisk
Within a text, an asterisk is typed directly after the final punctuation of the sentence it relates to, but before a dash.
Whenever an asterisk is placed within a text, a corresponding asterisk is placed at the bottom of the page, within the footer area, directly below the printed textual material. This footnote asterisk should contain some explanation, limitation, or elucidation of the text. An asterisk should precede any numbered footnotes at the bottom of the page.
Occasionally we see a newspaper or magazine article that contains a single asterisk within the text but does not include the corresponding footnote to indicate the meaning of the textual note. What is the purpose of this single asterisk smack dab in the middle of the text? No one knows; except, perhaps, the writer who put it there. Presumably, the author may have wanted to emphasize a particular point or give added importance to a statement. However, without a note at the bottom of the page, the reader has no clue as to what the asterisk stands for.
It is an error that, unfortunately, is seen too frequently today in printed material. So, it is best to always use an asterisk as a pointer. It points to a footnote at the bottom of the page!
Originally posted 8/4/2015 and happily updated 10/28/2017. Thanks for reading!