When to use IMG vs. CSS background-image?

web-development

responsive-design

performance

best-practices

byAnton Shumikhin·Nov 5, 2024

Opt for IMG tags when you're dealing with essential content needing alt text for accessibility and SEO — crucial for user interaction and for our search engine buddies.

<img src="coolPicture.jpg" alt="Cool picture of a cat on a roomba"> <!--No roomba cats were harmed in coding this line-->

Prefer CSS background-image for those decorative visuals that wouldn't affect the content's interpretation and don't require accessibility assistance.

.interesting-background {
  background-image: url('trippyPattern.png'); /* Stay groovy, my dudes */
}

To sum up: Content: IMG; Decoration: background-image.

Considering image responsiveness

If you find yourself tackling responsiveness and scaling issues, rest assured both <img> and CSS background-image have got you covered.

<img> tags make friends with the srcset attribute quite easily, allowing multiple size variations of an image to better suit different screen sizes and resolutions.

<img src="coffee.png" srcset="coffee-2x.png 2x, coffee-3x.png 3x">

When it comes to grand, full-window backgrounds, nothing beats a CSS background-image complemented by background-size: cover; as it adjusts without distortion to fit varying viewport sizes.

.background-hero {
  background-image: url('amazingView.jpg');
  background-size: cover; /* Covers as much as my college coffee consumption */
}

Balancing performance and interactivity

Balancing page performance and user interaction is key when considering image usage in HTML or CSS.

Animated transformations of <img> elements are delivered more smoothly by browsers, so they're the ones you call when aiming for slick animations.

<img class="animated-image" src="funAnimation.gif" alt="Animated image">

Can't forget about interactive elements, though. CSS backgrounds combined with :hover can make pretty engaging hover transitions for buttons or links.

.button:hover {
  background-image: url('hoverBackground.jpg'); /* Hover is like over for H(haudevs) */
}

Prioritizing accessibility and printing

When it comes to accessibility and printing, <img> tags are the undisputed champs. The alt attribute is a lifesaver for users needing assistive technologies, and these images get included in prints, a godsend for articles and learning materials.

<img src="essentialDiagram.jpg" alt="Decisive diagram explaining string theory">

For print exclusions, CSS background-image has your back. @media print rule ensures that backgrounds remain screen-only, saving trees and printer ink.

@media print {
  .non-printable-background {
    display: none; /* Trees love this */
  }
}

Optimizing code and ensuring compatibility

Looking to optimize code for faster loading or ensure compatibility across browsers? Both CSS background-image and <img> tags have their advantages.

CSS background-image is great for using image sprites to decrease HTTP requests and improve loading times for sites sprinkled with many small images/icons.

.icons {
  background-image: url('spritesheet.png');
  /* One sprite to load them all, One sprite to find them */
}

For animations and transitions, using -webkit-transition along with your CSS ensures smoother visuals across different browsers.

.navigation:hover {
  -webkit-transition: background-color 0.5s;
}

For universal browser support, especially with older models, <img> tags triumph with their wide compatibility.

<img src="logo.jpg" alt="Company logo"> <!-- Compatible with your grandpa's 2005 IE6 -->

Catering to SEO and viewer engagement

Never underestimate the power of <img> for SEO. Relevant images tagged with alt attributes can shoot your page’s ranking to the moon and spike user engagement through clickable and crystal-clear visuals.

<img src="interestingInfographic.jpg" alt="Data-rich infographic"> <!-- Google loves a good infographic -->

Building a dynamic, content-focused design

CSS background-image enables dynamic, flexible and site-wide design consistency. Switching graphics via classes and media queries, easing design modifications without touching the HTML.

.responsive-background {
  background-image: url('daytime.jpg');
}

@media (max-width: 700px) {
  .responsive-background {
    background-image: url('nighttime.jpg'); /* Sun's down, styles up */
  }
}