why use id's & class's in html why not just one?

Question

i understand what there is a difference between id\'s and class\'s - ids and ment to be given to a unique item, and class\'s and like tags, they can be given to multiple ite

Answer 1

#id is used to describe the document structure or important containers/elements and they must be unique entries.

.class is used to describe elements which are can be many elements in this documents.

If you try to validate the document and have many id's this will be error and if you want your document to be valid you must rename the id's of use classes.

Classes are useful because they can be many classes with one name on your document and you will not be force to copy/paste style from one element to another and change only the tag to describe the new element.