How to call a Class and ID in CSS

Class applies to a group of elements. To call a class, use a period ".". Example:

• In the file, the code is:

<header class="entry-header">
December 12, 2016
</header>

<aside class="entry-header">
January 1, 2015
</aside>

• In the CSS file, call it like this:

.entry-header
{
display:none;
}

ID applies to only 1 specific element. To call an ID, use a hashtag "#". Example:

• In the file, the code is:

<header id="entry-header">
December 12, 2016
</header>

• In the CSS file, call it like this:

#entry-header
{
display:none;
}