Difference between "div id" and "div class" in HTML

In addition to setting a style for a HTML element, CSS allows you to specify your own selectors called "id" and "class".
1.THE ID SELECTOR:
The id selector is used to specify a style for a
single, unique element.
The id selector uses the id attribute of the HTML
element, and is defined with”#".
The style rule below will be applied to the element
with id="abc":
#abc
{
Text-align: center;
Color: red;
}
2.THE CLASS SELECTOR:
The class selector is used to specify a style for a
group of elements. Unlike the id selector, the class
selector is most often used on several elements.
This allows you to set a particular style for many
HTML elements with the same class.
The class selector uses the HTML class attribute, and
is defined with a "."
In the example below, all HTML elements with
class="center" will be center-aligned:
.center
{
Text-align: center;
}
A class can be used several times, while an ID can
only be used once, so you should use classes for
items that you know you're going to use a lot. An
example would be if you wanted to give all the
paragraphs on your webpage the same styling, you
would use classes.Common id elements are things
like header, footer, sidebar. Common class elements
are things like highlight or external-link.


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