Why add ALT Text to an Image?

Adding ALT text to a website image is good for SEO, but is that all?

The image alt text is the short phrase that pops up when you hover over an image.

The alt text can also be shown when the image fails to load or download.

The alt text parameter associated with a website image is best known for its SEO requisite. However, it’s also important for Braille, screen readers and in case the image fails to download.

Oh, and if someone is viewing your website with the Lynx web browser.

Reasons to add Image alt Text

To summarise, adding descriptive text to your images is good for:

  • SEO
  • Search engine indexing
  • Braille readers
  • Screen readers
  • Disabled image download

SEO

SEO ranking is acheived through a number of factors. Amongst these is the quality of the underlying HTML code.

SEO includes adherence to the standards defined for website design and build.

Badly written website HTML code can adversely affect a website’s search engine ranking.

Included within badly written HTML code is the omission of the alt text from an image. So yes, not supplying this text can impact on your website.

Good alt text may also be used in promoting the web page and the image on the search image results. The text may help to have your image shown on the Google search results, image listing.

Search Engine Indexing

The search engine robots, crawling the Internet, are not able to interpret an image, understanding how you perceive it to be used.

For example, you have included a picture of a building on a web page. The alt text may be used to clarify its context. Perhaps you provided the interior design; your company is based here; as an architect it interests you; or maybe it’s simply a lovely building which inspires you.

Adding alt text to the image will clarify, to the search engine robot the context in which you are using the image.

Otherwise the only available reference info is the file name, and dependent upon the context within the surrounding text.

Screen Readers

A screen reader will convert the text on a web page to synthesised speech, or braille, allowing those with limited sight to browse the Internet, hearing the content of web pages.

Screen readers operate by converting the text content of a web page to either speech or braille. The text content for conversion includes not only the visible sentences of text but some of the underlying code to. To best understand a web page’s content a screen reader will handle elements such as tables and images by cleverly giving more information such as highlighting the table headers.

A screen reader will work best where the underlying HTML code is correctly structured. Making use of the less visible parameters such as the image alt text.

Simply having an image with no description, or the original camera file name won’t be of help.

Image Download Disabled

Disabling image download is the correct setting for best security, when configuring an email client.

Although not a page on your website it does illustrate the importance of adding a descriptive text to your images.

Why add alt Tex to an Image: Lynx Browser

A basic editor, such as Lynx doesn’t handle images. A useful tool if your desktop windowing system has crashed, or you are accessing via a terminal session.

Adding the alt Text

It’s really easy to add the alt text associated with an image.

The common CMSs all offer an easy option to add the descriptive text to the images.

For example WordPress, when editing an image in the media pages or on a page or post offers the alt text as a text box to be completed when editing an image. As shown in the image below.

Image alt Text WordPress Attachment Details

The WordPress CMS offers the appropriate text fields, when editing an image. Other CMSs do likewise.

If you are interested in how it’s implemented in HTML. It’s simply the addition of the parameter alt, as shown in the simplified version below, of the phone box image:

<img  src=”http://www.vntweb.co.uk/image-alt-text-wordpress-attachment-details.png” alt=”Image alt Text WordPress Attachment Details” />

Further Reading

For more information about why you should add alt text to your website images there’s a wikipedia screen reader article and RNIB has info about assistive technology, also read about the BBC’s view on accessability of their website with screen readers and WebAIM has details about designing for screen reader compatibility