Understanding ALT Attributes and Their Benefits for SEO

An ALT attribute is text that describes a picture. The ALT attribute helps search engine crawlers understand what a picture on a page is, without being able to see the picture. It’s information that you should use in your website’s HTML code to describe what an image is about. An ALT attribute is sometimes referred to as ALT text or, incorrectly, ALT tag. 

ALT attributes also help website’s visitor that are using a screen reader, have disabled all images, or are visually impaired. These attribute ensure that visitors can also understand what the image represents thanks to this attribute.

Good ALT attributes is a short description that conveys what a picture is about.

example of a good alt attribute An example of a good ALT attribute; the ALT attribute describes the image.  

ALT attributes are also crucial for search engine crawlers to understand what your website is about and to understand the pages within the website that it is crawling. Crawlers do not understand images the way the majority of your website visitors do; when they encounter an image, they can only read the site’s HTML code.

If you do not add an ALT attribute, crawlers will only be able to see that an image is there, but they will not understand what the image represents. 

example of a picture with no alt attribute

An example of a picture with a missing ALT attribute; crawlers can not crawl the ALT attribute.  

ALT Attributes & SEO

By using ALT attributes, you make it easier for the crawlers to index your site and place it higher in the search engines. The higher you are in the SERPs, the more visitors come to your site.

Effective ALT attributes will have a positive impact on your SEO. Not only will you be making your website more accessible for visitors, but your visibility in image results will also increase. Your overall visibility will be higher; which is great for your bottom line!

Adding ALT Attributes to Content

Many programs, like Wordpress, will tell you to add a title and description to the picture as soon as you upload it to your content creator. If you don't add it, it will simply use the filename of the uploaded photo, which may or may not describe the photo at all. The easiest and most efficient way to add ALT attributes to your photos is by using a content management system that allows you to describe the photo.

If you want to try to to code a an ALT attribute, you can do so as well. ALT attribute are part of the image tag, and  are used along with the source attribute .

The ALT attribute code should look similar to the one below:

<img src=”http://yourdomain.com/examplephoto.jpg” alt=”the description of the example photo”/>

Between the two attributes, you should insert a space. The value of those attributes should be written in double quotation marks.

Viewers on your site will see a picture of the example photo, and crawlers will see the ALT attribute "The description of the example photo."

Writing SEO Friendly ALT Attributes

Writing SEO friendly ALT attributes isn't always easy, but there are a few guidelines to follow if you want to make your ALT attributes crawlable, understandable and, maybe even appear in image searches!

Guidelines for Writing ALT attributes:

  • short, but descriptive (50 characters limit)
  • relevant to the image and the content on the website
  • simple and easy to understand
  • include keywords (but omit keyword stuffing)

Every image should have an ALT attribute, even if it is a decorative element or if you think it is irrelevant. According to the W3C standards, every image should have an ALT attribute, even if it’s just a decorative element. If it is a decorative element, simply leave the value as an empty string.

Hints for Adding ALT Attributes Easily

If you have a lot of images to add ALT attributes to, do the following:

  • Talk to your photographer and ask him to write descriptions to the images instead of naming them in a way that doesn’t say anything, e.g. “red shoes for women.jpg” instead of “DCIM123.jpg”.
  • Automate the process of inserting ALT attributes to the images with the help of your developer - ask him to write a script that enables that.
  • Use a CMS that asks you to add the description after uploading a photo!
  • Use Unamo SEO's On-Page Optimization tool to know exactly which images are missing ALT attributes on a page.