Home
>
Web Development
>
Writing Effective ALT Text For Images

Writing Effective ALT Text For Images

Anyone who knows anything about web accessibility knows that images need alternative, or ALT, text assigned to them. This is because screen readers can't understand images, but rather read aloud the alternative text assigned to them. In Internet Explorer we can see this ALT text, simply by mousing over the image and looking at the yellow tooltip that appears. Other browsers (correctly) don't do this. The HTML for inserting ALT text is:

img src="filename.gif" alt="Alternative description goes here"

But surely there can't be a skill to writing ALT text for images? You just pop a description in there and you're good to go, right? Well, kind of. Sure, it's not rocket science, but there are a few guidelines you need to follow...

Spacer images and missing ALT text

Spacer images should always be assigned null ALT text, or alt="" . This way most screen readers will completely ignore the image and won't even announce its presence. Spacer images are invisible images that pretty most websites use. The purpose of them is, as the name suggests, to create space on the page. Sometimes it's not possible to create the visual display you need, so you can stick an image in (specifying its height and width) and voli?, you have the extra space you need.

Not everyone uses this null ALT text for spacer images. Some websites stick in alt="spacer image". Imagine how annoying this can be for a screen reader user, especially when you have ten of them in a row. A screen reader would say, "Image, spacer image" ten times in a row (screen readers usually say the word, "Image", before reading out its ALT text) - now that isn't helpful!

Other web developers simply leave out the ALT attribute for spacer images (and perhaps other images). In this case, most screen readers will read out the filename, which could be 'newsite/images/onepixelspacer.gif'. A screen reader would announce this image as "Image, newsite slash images slash one pixel spacer dot gif". Imagine what this would sound like if there were ten of these in a row!

Bullets and icons

Bullets and icons should be treated in much the same way as spacer images, so should be assigned null alternative text, or alt="". Think about a list of items with a fancy bullet proceeding each item. If the ALT text, 'Bullet' is assigned to each image then, "Image, bullet" will be read aloud by screen readers before each list item, making it take that bit longer to work through the list.

Icons, usually used to complement links, should also be assigned alt="". Many websites, which place the icon next to the link text, use the link text as the ALT text of the icon. Screen readers would first announce this ALT text, and then the link text, so would then say the link twice, which obviously isn't necessary.

(Ideally, bullets and icons should be called up as background images through the CSS document - this would remove them from the HTML document completely and therefore remove the need for any ALT description.)

Decorative images

Decorative images too should be assigned null alternative text, or alt="". If an image is pure eye candy then there's no need for a screen reader user to even know it's there and being informed of its presence simply adds to the noise pollution.

Conversely, you could argue that the images on your site create a brand identity and by hiding them from screen reader users you're denying this group of users the same experience. Accessibility experts tend to favour the former argument, but there certainly is a valid case for the latter too.

Navigation & text embedded within images

Navigation menus that require fancy text have no choice but to embed the text within an image. In this situation, the ALT text shouldn't be used to expand on the image. Under no circumstances should the ALT text say, 'Read all about our fantastic services, designed to help you in everything you do'. If the menu item says, 'Services' then the ALT text should also say 'Services'. ALT text should always describe the content of the image and should repeat the text word-for-word. If you want to expand on the navigation, such as in this example, you can use the title attribute.

The same applies for any other text embedded within an image. The ALT text should simply repeat, word-for-word, the text contained within that image.

(Unless the font being used is especially unique it's often unnecessary to embed text within images - advanced navigation and background effects can now be achieved with CSS.)

Company logo

Websites tend to vary in how they apply ALT text to logos. Some say, 'Company name', others 'Company name logo', and other describe the function of the image (usually a link back to the homepage), 'Back to home'. Remember, ALT text should always describe the content of the image so the first example, alt="Company name", is probably the best. If the logo is a link back to the homepage then this can be effectively communicated through the title tag.

Conclusion

Writing effective ALT text isn't too difficult. If it's a decorative image then null alternative text, or alt="" should usually be used - never, ever omit the ALT attribute. If the image contains text then the ALT text should simply repeat this text, word-for-word. Remember, ALT text should describe the content of the image and nothing more.

Do also be sure also to keep ALT text as short and succinct as possible. Listening to a web page with a screen reader takes a lot longer than traditional methods, so don't make the surfing experience painful for screen reader users with bloated and unnecessary ALT text.

This article was written by Trenton Moss. He's crazy about web usability and accessibility - so crazy that he went and started his own web usability and accessibility consultancy ( Webcredible - http://www.webcredible.co.uk ) to help make the Internet a better place for everyone.

quick home cleaning Park Ridge ...

In The News:

Daimler Truck's Oregon demos show how a Freightliner Cascadia's automatic emergency braking responds when dummy cars suddenly cross a moving truck's path.

Facebook ads promising to recover stolen funds are targeting scam victims again, and Meta confirmed removing flagged accounts after investigation.

Tesla Cybertruck production is winding down at Gigafactory Texas to make room for Cybercab robotaxi manufacturing, but key questions remain for owners.

Identity theft can hide in phone accounts, medical records and utility bills long before it shows on a credit report. Eight places to check now.

JR East's towering ZIZAI ZX-3 chainsaw robot tackles dangerous branch-cutting along Japan's Koumi Line while a trained operator controls it remotely.

A massive DHS data leak exposed records of over 41,000 employees, revealing links to undercover ICE operations, Palantir tools and AI platforms.

The Fox News AI Newsletter covers the latest artificial intelligence technology advancements, including the challenges and opportunities AI presents now and for the future.

UCLA's PhoneBot turns old Android phones into the brain of a two-legged humanoid robot that walks, follows people and stands up after falling.

A fake Amazon invoice charging $988.18 for an iPad lists the same customer support phone number three times to steer panicked victims into calling.

A handful of food delivery robots from Uber Eats and other platforms have gotten kicked and knocked over in Philadelphia and Los Angeles.

Data broker opt-out forms may not protect your family. People search sites can still expose your info through a spouse's or parent's profile.

Apple's first touchscreen MacBook Pro starts at $2,899 with a PROLED XDR OLED display, but the non-touch M6 model costs $900 less at $1,999.

Black Friday deals are already drawing scammers who use fake delivery notices and gift card payment requests to steal your personal financial information.

Apple's iPhone Duo reportedly outlasted the Samsung Galaxy Z Fold 8 by over three hours in battery tests, but its weight and repair costs raise concerns.

Florida Polytechnic University's Jetson ONE eVTOL police vehicle named Astro still awaits FAA authorization before officers can fly operational patrols.

OpenAI's new locked chats feature lets you protect ChatGPT conversations with a PIN, Face ID or Touch ID, but there are key privacy limitations.

A phishing email disguised as an Evite fooled a man even after he emailed his friend to verify it, revealing how compromised Gmail accounts aid scams.

Microsoft's AI diagnostic system identified 83% of complex medical cases in a study, more than doubling the 36% accuracy of generalist doctors.

Account takeover threats go beyond stolen passwords as criminals exploit session cookies, SIM swaps and MFA fatigue to bypass your login security.

SpaceX is reportedly pursuing access to 80,000 cell sites to turn Starlink into a major wireless carrier rivaling Verizon, AT&T and T-Mobile.

Tech advocacy groups warn that foreign nationals at AI companies like OpenAI and Google pose a national security threat amid a lack of federal oversight.

Singapore researchers built the world's first touchscreen woven into clothing, surviving 50 machine washes while displaying images and responding to touch.

The Fox News AI Newsletter covers the latest artificial intelligence technology advancements, including the challenges and opportunities AI presents now and for the future.

A startup founder woke to $449 in unexpected OpenAI and Anthropic charges after stolen API keys were exploited during the "Black October" cyber wave.

Educational Testing Service hackers stole millions of California student records, but families who moved out of state years ago may also be affected.

Writing Effective ALT Text For Images

Web Development