Images are an area of WordPress SEO that are often overlooked. Yet they can be important in driving traffic to your site.
In this post, I combine extensive research with my own experience of WordPress SEO. The end result is the definitive guide to making the images on your WordPress website search engine friendly. I will offer some simple tips on how to make images a central part of your WordPress SEO strategy.

But search engines can’t read images!

One reason that images are often overlooked in WordPress SEO – and SEO in general – is that search engines can’t actually understand them. Search engines can only read actual text on a web page. They can’t interpret pictures, or even images with text embedded in them.
Fortunately, search engines do have mechanisms for understanding images. Whenever you upload an image to your website, you can tag this with ‘meta data’ that helps machines to understand the image. This includes screen readers for people with visual impairments, web browsers that cannot display images, and of course search engines.
For example, an image of the WordPress logo could have alt text (a type of meta data) saying ‘WordPress logo’. This tells machines that it’s an image of the WordPress logo.
This allows you to make your WordPress images SEO friendly.

Tips for creating WordPress SEO images

WordPress’ SEO features makes it easy to create search engine friendly images.

Adding an SEO image in WordPress

Whenever you add an image, simply complete the fields in the ‘Add media’ window:

Explanation and tips for each of the WordPress ‘Add image’ fields

Field name	What to enter here
Title	WordPress will automatically add your image filename here. You might want to change it to something more descriptive and SEO friendly.Image titles are important for SEO. The title will also appear when you hover over the image.
Alternate Text	This is more commonly known as ‘alt text’ or the ‘alt tag’. It should contain a brief description of the image.
Caption	Enter text here if you want to display a caption underneath the image. It’s generally thought that this doesn’t help with SEO, but no one knows the search engine algorithms for definite. If you’re using a caption anyway, it doesn’t hurt to include the main keyword for your WordPress post or page.
Description	Enter a longer description of the image here. It’s thought that this isn’t a huge factor for search engines, but it can help a bit. Make sure it’s descriptive as well as containing your main keywords.
Link URL	The end of your link URL will be the original filename of your image. So before uploading the image, it won’t hurt to make sure the filename contains the main keyword for your WordPress page or post.
Size	Most articles on WordPress SEO images don’t mention image size, but this is important too. Search engines reward fast loading websites and penalise slow ones with large images.WordPress helps with SEO by automatically resizing images as needed. To use this SEO feature, simply click Thumbnail, Medium or Large and WordPress will resize the image accordingly. Never click ‘Full size’ unless you have previously sized the image using software such as Photoshop.I recommended that you always size images before uploading them to WordPress. Website images should be set to the required number of pixels rather than worrying about the resolution. Before uploading an image to WordPress, you can optimise it using free software such as PNG Gauntlet. This will compress it as much as possible without losing quality.

Putting your WordPress SEO image in context

Most people don’t know that search engines also look at the context of an image. This means that as well as the image meta data, search engines look at the title and url of the WordPress page or post where the image is situated, as well as the text around the image. If these include your main keywords then search engines will know that the image is related to those keywords.
When adding an image to your WordPress website, think about its overall context. For example, put relevant keywords in the text close to the image.

WordPress SEO plugins to do the hard work for you

If the above sounds like too much work, you’ll be pleased to discover a WordPress SEO plugin that will do much of the work for you.
I would always recommend manually adding titles and alt text for each image on your WordPress site. This will generally be more effective than a plugin that can do it automatically.
But if you really can’t be bothered – and lots of people can’t – then the WordPress SEO Friendly Images plugin covers the main points for you. It automatically uses the post title to set the image’s title and alt tag. This is useful because you should always include your main SEO keywords in the title of your WordPress post or page anyway. The plugin will use this to automatically optimise your images.

But is the extra traffic to your WordPress website worth having?

Most articles on SEO images seem to assume that using images to drive extra traffic to your website is a good thing. While it’s obviously not a bad thing, it may not be as valuable as people suggest.
The main benefit of optimising your images is that is makes them more likely to rank highly in the image search results – for example, Google images. So when people do an image search using your main keywords, an image on your site is more likely to appear.
In most cases, I think this is much less important than ranking highly in the main search results for your keywords. This is because people searching for images have very different intentions to people searching for websites.
For example, most people who search Google for ‘WordPress web design’ will be actively seeking a WordPress web design agency such as Barn2 Media. This is traffic we definitely want! On the other hand, people searching Google images for ‘WordPress web design’ are more likely to be looking for something different – such as images to put on their own website promoting WordPress web design. This traffic is much less important to us!
If images are your core business then you should obviously spend a lot of time optimising your WordPress SEO images. This applies to photographers, graphic designers, etc.
For the majority of WordPress website owners, it’s slightly less important. You should always optimise your images for SEO because not doing so is a wasted opportunity. If you don’t have time to do it manually then use WordPress SEO Friendly Images to do it for you. But don’t get too caught up in it, as the rewards may be lower than for other types of SEO.

Do images help with my WordPress website’s overall SEO and PageRank?

Although this is a grey area, there’s evidence to suggest that optimising images can boost your website’s position in the main search results, as well as image searches.
In deciding whether your website is relevant for a particular keyword, search engines look at how often the site contains those keywords, and in what way. As well as the usual SEO factors – page title, url, body text, headings etc. – image meta data can provide important clues about the content of your website. If this can help with your overall search engine ranking then this is definitely worth doing.

Further reading

I always recommend the Yoast tutorial as the definitive guide on WordPress SEO in general. This is a great starting point for making your WordPress website search engine friendly.