What Alt Text Is and Who Uses It
Alt text, short for alternative text, is a written description attached to an image. Screen readers, which are tools that read page content aloud or send it to a braille display, use it to tell someone what an image shows. It also appears if an image fails to load, and search engines may use it as one clue about what the image contains.
People with low vision or blindness are the most obvious audience, but they are not the only one. Someone on a slow connection, or someone who has turned off images, may rely on the same text. Writing it is a small effort that makes your profile, website or posts more usable.
Accessibility needs and tools differ from person to person, and there is no single perfect description. The goal is to be helpful, not exhaustive.
Start With the Purpose of the Image
The most useful question is: why is this image here? The answer decides what to write.
- The image carries information. Describe the information. For a chart, say what the chart shows, not that it is a chart with colored bars.
- The image sets a mood or illustrates a point. Give a brief description of what is shown, keeping it short.
- The image is purely decorative. A divider line or background pattern adds nothing for someone who cannot see it. Many platforms and website tools let you mark an image as decorative, or you can leave the alt text empty so a screen reader skips it.
- The image is a link or button. Describe where the link goes or what it does, not the picture itself.
The same photograph can need different descriptions in different places. A picture of a conference stage might be described in one sentence in a blog post about the event, and in more detail if the stage layout is the point.
Writing Good Descriptions
A few habits make alt text clearer.
Be specific and brief. One or two short sentences is often enough. Concrete wording beats vague wording. Compare “A person outside” with “A woman in a gray jacket speaking into a microphone at an outdoor event.”
Lead with the important part. Put the key detail first, since some people skip ahead.
Skip “image of” and “photo of.” Screen readers usually announce that an element is an image already. Starting with these words repeats it. Mentioning the type can still help if the style matters, for example “Pencil sketch of a lighthouse.”
Include text that appears in the image. If a graphic contains a quote or a date, repeat that text in the description so it is not lost.
Describe what matters, not everything. You do not need to list every object in a crowded scene. Pick what supports your message.
Avoid keyword stuffing. Cramming in search phrases makes the experience worse for the people the text is meant to help, and search engines may treat it as low quality. Write for a reader first.
Examples
These are hypothetical examples to show the idea.
- A headshot on an about page: “Smiling man with short dark hair wearing a navy shirt, against a plain light background.” Often a name appears beside the picture, so a short description is fine.
- A bar chart in a report: “Bar chart showing website visits rising each month from January to June, with the highest bar in June.” If exact numbers matter, put them in the surrounding text or a small table.
- A social media graphic with a quote: Repeat the quote, then add a few words about the design only if it adds meaning.
Where Alt Text Goes
Most major tools offer a field for it. In website editors it is usually next to the image upload. Some social platforms provide an option to add a description before posting, and some can also generate one automatically. Features change over time, so check the current options in the app you use. Automatic descriptions can be a decent starting point, but they can miss context or get details wrong, so reading and correcting them is a good habit.
For a graphic you create yourself, include any essential information in the post text as well. This helps people who cannot see the image and also those who skim.
Beyond Alt Text
Alt text is one piece of accessible visuals. A few related points:
- Contrast. Light gray text on a white background is hard for many people to read. Strong contrast between text and background helps everyone, including people viewing a screen in bright light.
- Text in images. Avoid placing long passages of text inside a picture. If you must, repeat it in the caption or post.
- Do not rely on color alone. If a chart uses red and green to mean different things, add labels or patterns as well. Some people have difficulty telling certain colors apart.
- Captions for video. Videos benefit from captions for people who are deaf or hard of hearing, and for anyone watching without sound.
- Plain wording. Clear descriptions follow the same principles as plain language elsewhere in your writing.
Accessibility and Your Professional Image
Thoughtful description signals care for your audience, which fits into a wider approach to trust and credibility. It is not a trick for gaining followers, and no one should expect a guaranteed result from adding it. It is simply a considerate default.
If you are starting from scratch, a manageable plan is to add alt text to new images going forward, then update your most visible older ones, such as the images on your main web pages, as time allows. Aiming for steady improvement is more realistic than trying to fix everything at once.