It is used to apply style to any and every element present in a web page and it is an asterisk. It is used as
* {
margin: 10px 0;
}
margin: 10px 0;
}
It is not usually used. It can also be used to apply a style to all of the tags that descend from a particular page element like #top * selects every tag inside the page element to which the #top ID is applied.
