An asterisk is a small star-shaped symbol (*) used to highlight or draw attention to something important or to indicate that additional information or conditions apply. Full definition
The press release, written by the artist, made a superficial concession to universality by supplanting place names with asterisks in a narrative based on events in the lives of Brazda's family, as if these experiences could happen to anyone, anywhere. (artforum.com)
In fact, I don't even know my card number as the middle 6 digits have been replaced with asterisks in the bill. (money.stackexchange.com)
A few fields in the application form are marked with a sign of asterisk indicating that all these marked fields have to be necessarily filled. (policybazaar.com)