between the ID and class :

Both ID and class is been used in HTML and assigns the value from CSS.

Class	Id
We can apply a class to various elements so that it could be numerous times on a single page.	The Id is unique in a page, and we can only apply it to one specific element.
The class is assigned to an element and its name starts with "." followed by the name of the class.	The name of the Id starts with the "#" symbol followed by a unique id name.
We can attach multiple class selectors to an element.	We can attach only one ID selector to an element.
Syntax: .class{ // declarations of CSS }	Syntax: #id{ // declarations of CSS }