Images Best Practices in HTML/CSS

In this article, we will learn about the best practices for using images in HTML/CSS.

Use the correct image format

There are several image formats available, but the most common ones are JPEG, PNG, and GIF. Each format has its own advantages and disadvantages, so it’s important to choose the right format for your images.

• JPEG: Best for photographs and images with lots of colors. It uses lossy compression, which means that some image quality is lost when the image is compressed.

• PNG: Best for images with transparency or sharp edges, such as logos and icons. It uses lossless compression, which means that no image quality is lost when the image is compressed.

• GIF: Best for simple animations or images with a limited color palette. It uses lossless compression, but it only supports 256 colors.

Responsive Images

Responsive images are images that scale with the size of the screen. This is important because it ensures that your images look good on all devices, from smartphones to desktops.

To make an image responsive, you can use the max-width: 100%; CSS property. This property ensures that the image will never be wider than its container, which means that it will scale with the size of the screen.

img {
  max-width: 100%;
  height: auto;
}

Lazy Loading

Lazy loading is a technique that delays the loading of images until they are needed. This can help improve the performance of your website, especially on pages with lots of images.

To lazy load images, you can use the loading="lazy" attribute in the <img> tag. This tells the browser to only load the image when it is in the viewport.

<img src="image.jpg" alt="Image" loading="lazy">

CSS Background Images

Instead of using the <img> tag, you can also use CSS to set images as background images. This can be useful if you want to add images to elements that are not natively supported by the <img> tag, such as <div> or <span>.

div {
  background-image: url('image.jpg');
  background-size: cover;
}

Picture Element

The <picture> element is a new HTML5 element that allows you to define multiple sources for an image based on different conditions, such as screen size or pixel density.

This can be useful if you want to serve different images to different devices, such as high-resolution images to devices with retina displays.

<picture>
  <source srcset="image-large.jpg" media="(min-width: 1024px)">
  <source srcset="image-medium.jpg" media="(min-width: 768px)">
  <img src="image-small.jpg" alt="Image">
</picture>

Use object-fit property

The object-fit property in CSS allows you to specify how an image should be resized to fit its container. This can be useful if you want to control how an image is displayed, such as stretching it to fill the container or preserving its aspect ratio.

img {
  width: 100px;
  height: 100px;
  object-fit: cover;
}