Difference between an id and class in HTML?

If you’re interested in learning more about CSS selectors, read our beginner’s guide to CSS selectors . In CSS , selectors are used to target a specific element or range of elements on a web page. Once an element has been targeted, a style or set of styles can be applied to the element. As we discussed earlier, the ID selector can only be used to style one element. This is because IDs can only be used once on a web page. Classes, on the other hand, can be used across multiple elements. So, if you apply a style using a class selector, any element which shares that class will be subject to the styles you define.

If both the class and id are applied to the same element the color will be red. Only the font-weight of the class selector is applied from to class since it wasn’t specified by the id. CSS does actually care in that IDs have much higher specificity than classes. This obviously needs thinking about in terms of which CSS rules will override each other in any given set of style sheets.

The difference between Class and ID selector

In advanced development ids we can basically use JavaScript. Finally, when it comes to selector performance and precedence, ID tends to win out.

• It’s funny…when I was first starting out with CSS, I was confused as to what the differences were between IDs and classes too.
• The difference between an ID and a class is that an ID is only used to identify one single element in our HTML.
• If you are purely an HTML/CSS person, this attitude can persist because to you, they really don’t seem to do anything different.
• The selectors in CSS are part of the CSS ruleset and used to select the content we want to style.
• In such cases, try to avoid classes which are being used for applying CSS and rather add new classes which doesn’t have corresponding CSS.
• With the advent of jQuery and other Javascript frameworks this is pretty much a non-issue now.

The simple difference between the two is that while a class can be used repeatedly on a page, an ID must only be used once per page. Therefore, it is appropriate to use an ID on the div element that is marking up the main content on the page, as there will only be one main content section. In contrast, you must use a class to set up alternating row colors on a table, as they are by definition going to be used more than once. I’m with Dan, it took me a couple of years to figure out that you could add two classes to an element.

Class selector

The key thing that I kept getting confused with is this – there ARE no stylistic differences between an ID and a class. The only differences are in how they’re used, not how the browser displays them. As soon as I realized that, everything else got much easier. Nope, “secondaryContent” would be more appropriate since sidebar is still a presentational description.

In years gone by IDs were also preferred because they’re easily accessible in Javascript . With the advent of jQuery and other Javascript frameworks this is pretty much a non-issue now. It’s okay to put multiple students under one Class title, such as Biology. But it’s never acceptable to put multiple students under one student ID. No two students on campus will have the same student ID card. However, many students can and will share at least one Class with each other. It is written with the hash character (#), followed by the id of the element.

CSS Class vs ID Selectors

You should do a poll on how long it took people to figure out that you can have multiple classes… It too me a good number of years. No sites that I went to ever brought it up and I never really noticed it when viewing other website’s code.

• However, one of the paragraphs is assigned an ID which allows individual properties to be set for this particular paragraph.
• This behavior works because IDs are unique on a web page.
• It is written with the hash character (#), followed by the id of the element.
• I didn’t really understand what they meant, so I did a quick test.
• This obviously needs thinking about in terms of which CSS rules will override each other in any given set of style sheets.

An ID here of “sidebar” would be more appropriate. Information that is reusable should be kept in a class and information that is totally unique should be kept in an ID. You are working on one site and figure out that applying a particular class name fixes a problem you are having.

IDs Are Used by JavaScript

It’s so encouraging to see that others have struggled with CSS. I almost gave up because I thought I was too slow. Thanks for a very interesting and well documented article.

The class selector selects elements with a specific class attribute. It matches all the HTML elements based on the contents of their class attribute. Symbol, along with the class name, is used to select the desired class. So far, we have discussed the fact that IDs can only apply styles to one element.

We already know this element is a link, it’s an anchor element! No particular need here to apply a class, as we can already apply styling via its tag. Class is for applying your style to a group of elements. ID styles apply to just the element with that ID . Usually you use classes, but if there’s a one-off you can use IDs . Technically you can use classes for all of it, or split them up logically. You can not, however, reuse id’s for multiple elements.

Maybe by some stroke of luck I managed to never repeat ID elements. JavaScript people are already probably more in tune with the differences between classes and ID’s. JavaScript depends on there being only one page element with any particular id, or else the commonly used getElementById function wouldn’t be dependable. For those familiar with jQuery, you know how easy it is to add and remove classes to page elements. It is not the responsibility of JavaScript to manipulate these values, it would cause more problems than it would be worth. The iPod will also have a serial number on it which is absolutely unique to any other iPod in the world. It could, but for the store this wouldn’t be a very efficient way to store and use that data.

I think I only learned recently that only one element on the page should have a certain ID. I guess pages still render if you have multiple ones though?

Maybe it was just how I taught myself HTML and CSS. When I was first learning this stuff, I heard over and over that you should only use ID’s once, but you can use classes over and over. It basically went in one ear and out the other because it sounded more like a good “rule of thumb” to me rather than something extremely important. If you are purely an HTML/CSS person, this attitude can persist because to you, they really don’t seem to do anything different. In Html DOM both id and class are the element selector and are used to identify an element based on the name assign to these parameters. Please use ide.geeksforgeeks.org, generate link and share the link here.

The example of the class selector is given as follows. With help from Career Karma, you can find a training program that meets your needs and will set you up for a long-term, well-paid career in tech. If you have any experience using JavaScript , you’ll know that IDs are commonly used in that programming language. The function getElementById allows you to select an element on a web page. It relies on the fact that only one element can share the same ID.