How do you optimize images for search?
guide // , 5 min read, by Darthwares
Images are crucial for search engine optimization because, as Google documents, they can help people discover your site through visual searches. Optimizing images ensures both users and search engines, such as Google, can find and understand them, contributing to a better user experience and faster loading times. While images are integral to nearly every page, they often account for most of the downloaded bytes, making their optimization a key factor in website performance. Efficient image optimization can lead to significant byte savings and overall performance improvements.
On this page // 6 sections
The short version
- Optimize images to help users discover your site, for example through Google's visual search, and improve page performance.
- Use high-quality, clear images placed near relevant text.
- Write descriptive alt text to help Google and other search engines understand image content, and for accessibility.
- Implement responsive images to adapt to different devices and improve loading speed.
- Choose modern image formats like WebP or AVIF for better compression, and prefer vector images when suitable.
Why optimize images for search?
Images are an integral part of nearly every web page and, as Google documents, can be how people find your website for the first time, especially through visual searches. Google also documents that as you add images to your site, it is important to ensure that both people and search engines can find and understand them.
However, images often account for most of the downloaded bytes on a page. This means that optimizing images can yield some of the largest byte savings and performance improvements for your website. When the browser has fewer bytes to download, there is less competition for the client's bandwidth, allowing assets to download and display faster.
The very first question to ask is whether an image is, in fact, required to achieve the effect you are after. If you can eliminate an image resource, which often requires a large number of bytes relative to HTML, CSS, JavaScript, and other assets on the page, then that is always the best optimization strategy.
What makes an image high quality for search?
Google documents that using high-quality images gives users enough context and detail to decide which image best matches what they were looking for. This means images should be sharp and clear.
Additionally, placing images near text that is relevant to their content is important. The text that is near images can help Google better understand what the image is about and what it means in context to your page.
How does alt text help search engines and users?
Alt text, or alternative text, is a short but descriptive piece of text that explains the relationship between the image and your content. Google documents that it helps search engines understand what your image is about and the context of how your image relates to your page, making good alt text quite important for search engine optimization.
Beyond search engines, providing meaningful descriptions via the `alt` attribute on `img` elements also helps make your site more accessible by giving context to screen readers and other assistive technologies.
You can add alt text to your HTML with the `alt` attribute of the `img` element. Alternatively, your content management system (CMS) may have an easy way to specify a description for an image when you are uploading it to your site.
How do responsive images improve user experience?
With responsive web design, not only can page layouts change based on device characteristics, but images can as well. This approach ensures that images adapt appropriately to different screen sizes and resolutions.
To prevent images from accidentally overflowing their containers, it is important to use relative sizes for images. When a raster image is required, serving responsive images is recommended to provide an optimal experience across devices.
The `srcset` attribute enhances the behavior of the `img` element, making it easy to provide multiple image files for different device characteristics. Similarly, the `picture` element defines a declarative solution for providing multiple versions of an image based on various characteristics, such as device size, resolution, or orientation.
Which image formats should you use?
The very first question you should ask yourself is whether an image is, in fact, required to achieve the effect you are after. If you can eliminate an image resource, which often requires a large number of bytes relative to HTML, CSS, JavaScript, and other assets on the page, then that is always the best optimization strategy.
For images that consist of less complex geometric shapes, such as logos, text, or icons, vector formats are ideally suited. Web.dev advises preferring vector images whenever possible, as they are resolution-independent and always deliver sharp results.
When a vector image is not suitable, that is when you should be using a raster image format such as PNG, JPEG, WebP, or AVIF. Web.dev also states that WebP and AVIF will generally provide better compression than older formats, and should be used where possible. Efficiently encoding an image that is an LCP (Largest Contentful Paint) candidate is crucial to improving LCP.
Common questions
Why are images important for search?
As Google documents, images can be how people first find your website, especially through visual searches, and they are an integral part of every page. Optimizing them helps ensure both users and search engines, such as Google, can find and understand your content.
What is alt text for images?
Google documents that alt text helps search engines understand the image's context and makes your site more accessible by providing descriptions for screen readers and other assistive technologies.
How do responsive images work?
Responsive images allow images to change based on device characteristics like size or resolution. This is achieved using attributes like `srcset` or the `picture` element, which provide multiple image files or versions tailored for different devices.
Which image formats offer the best compression?
WebP and AVIF generally provide better compression than older formats. Web.dev recommends using these modern formats where possible to improve performance and reduce downloaded bytes.
What is the best image optimization strategy?
The best optimization strategy is to eliminate an image resource if it is not truly required. Images often account for a large number of downloaded bytes, so removing unnecessary ones can lead to significant performance improvements.
Primary sources and further reading
This article was researched and written by an AI model and published automatically. It was written from sentences that were checked to appear on the pages below, but a person has not reviewed the text. If something is wrong, tell us at chibivikramathithan@darthwares.com and we will correct it.