You have spent considerable time optimising your website’s content: your headers, sub-headings, title tags and meta descriptions are just right and you are now ready for Google to start discovering your content.
But wait. Have you considered your images?
Google pulls a substantial amount of clickable images into its main text results, as well as into its ‘Images’ tab.
This means that your text results will be pushed further down the page and people are more likely to click on the top content.
In fact, almost 38% of Google’s search engine results pages (SERPs) show images (source: Moz).
This means that if you are not optimising your on-page images, you could well be missing out on vital SERP real estate.
So where should you start with image optimisation? Alt text of course!
What is alt text?
Alt text is the shortened version of ‘alternative text’.
It is the short, written description which appears in the place of an image on a webpage if the image cannot be viewed for some reason.
This might be that the image fails to load or else has become broken.
Alt text is also known as alt tags or alt descriptions. And yes, it is a ranking factor. It helps search engines to crawl and rank your website or blog.
Why is alt text important?
Alt text is important for both your website’s accessibility and for search engine optimisation.
However, it is also important that it is written well, rather than just being added for content’s sake.
Alt text helps visually impaired users
Screen-readers, often used by visually impaired users, describe the image using the alt text. These makes your website more accessible to anyone who is blind or has a visual impairment. Find more tips for web accessibility here.
Alt text can also be useful for people who have learning disabilities or issues with sensory processing.
Alt text describes an image
Alt text provides a description of the image and adds semantic meaning to it.
Because of this, search engines use this text to return results.
If your alt text is well written, it will give search engines better information and help your pages to rank higher.
For some purposes, users will want to see an image, rather than read an article. For example, the search term “what does a banana look like?” is more suited to image results than text results.
Google Images is the second largest search engine in the world and is responsible for over 20% of all online searches (source: SparkToro).
How best to add alt text to your images
Most website content management systems make adding alt text to an image easy.
If you are uploading the image to the page, there may be an option on the upload screen to add it in.
If you are updating the alt text, clicking on the image should bring up image optimisation options where you can simply update the alt text.
What makes good alt text?
Unfortunately, it is not just a case of filling in your alt text fields with any old copy. If only it was that simple!
If your alt text is poorly written, it can actually harm your site’s accessibility and rankings.
4 tips to create good alt text for your images
Here are four useful tips to help you create good alt text for your images:
1. Keep your alt text specific and succinct
No one wants a rambling alt text which would be more at home as a description in a novel.
Try to briefly describe the image in a few words. Sometimes a full sentence may be needed.
Some screen readers truncate alt text to around 125 characters so it is a good rule of thumb to stick to this limit.
2. Describe the type of image you see
It is a good idea to help people understand the content of the image.
You can do this by explaining the type of image you have used. For example, you might say ‘headshot’, ‘illustration’ or ‘graph’.
3. Include any text that is part of an image
Screen readers are unable to read text which is on an image.
This means that you should include any text used as part of your alt text instead.
You do not need to do this if you have included the text as part of your content.
4. Review your spellings
Misspellings in your image alt text may harm user experience or even confuse search engines when they are crawling your site.
Review your alt text just as you would the rest of the content on your page.
Grammarly is a good online tool to use to help get your spelling and grammar just right.
Example of good alt text: Yellow banana fruit on blue surface
Bad alt text
Just as there is great alt text, there is also bad or poorly put together alt text.
Here are some things to avoid when you are writing yours:
Leave out “image of”
It will be obvious to both users and technology when they are accessing alt text and that it represents an image.
Therefore, there is no need to include “image of” or “picture of” at the beginning of your alt text.
Do not stuff your alt text with keywords
Just as with your blog or webpage content, you can be ranked-down for keyword stuffing in your alt text.
The primary purpose of your alt text should be to describe what is actually in the image, so make sure any keywords you use are being used truthfully.
Do not repeat yourself
If alt text repeats what is already on the page, then you do not need to duplicate that.
Feel free to leave it out if it is not needed.
Do not add alt text to decorative images
You should only add alt text to your illustrative images.
You should leave the alt text field blank for any images which are purely for decoration purposes, such as borders or separators.
Example of bad alt text: ‘banana’, ‘fruit’, ‘fruit bowl’, ‘fruit and vegetables’, ‘yellow’
Alt text on social media
Did you know that you can also add text to some social media images?
Twitter and Instagram both have this feature. The alt text is not visible on the image or caption but anyone using assistive technology such as a screen reader will have access to it.
This is great for building an accessible brand and ensuring that no users are excluded from accessing your content.
It is thought that alt text on these social media platforms may also help the reach of your post, with it being discoverable for more key words and search terms.