Alt text improves accessiblity and search engine optimization (SEO). But what is alt text, and how can you use it to your advantage and to help readers? Alt tags appear in the code of an HTML page and are used by screen readers to convey the context and meaning of an image.
In this blog post, we’ll explain alt text, its purpose, image alt text best practices, and more so you know how to write it for search engines and screen reader users.
Key Takeaways
- Alt text is a descriptive text associated with digital images used for accessibility and SEO purposes.
- Screen readers read alternative text aloud to assist visually impaired users in understanding the image’s content and context. Search engine bots use alt text to index the web page’s content.
- Alt text should be descriptive, concise, and relevant to the image; avoid redundancy or keyword stuffing.
- Different types of images require different levels of alt text detail. Decorative image alt text can have an empty alt attribute, while informative or functional images require more descriptive descriptions.
- Content management systems allow users to add and edit alt text easily when uploading or using an image on their websites.
Alt Text Definition
Alt text, also known as alternative text or alt attributes, is descriptive text used to describe an image on a web page.
Its purpose is to provide a text alternative for people who are visually impaired and use screen readers. If an image fails to load, alt text also tells users what was supposed to be shown.
Alt text helps visually impaired users understand the image’s content and web page’s context. Screen readers, such as Microsoft Narrator, JAWS, and NVDA, read the alt text aloud when encountering images, enabling users to understand the content and context of the visuals on a web page or app.
Another important aspect of alt text is its role in search engine optimization (SEO). Search engine bots can’t interpret images directly, so they rely on the alt tag to index and better understand the content of a page. By providing accurate, relevant, and appropriate alt text, website owners can improve the chances of their pages appearing in search results for specific keywords.
In order to write effective alt text, it’s important to keep it concise and descriptive, focusing on the key aspects of the image. Avoid using unnecessary phrases like “image of” or “picture of,” as automatic readers automatically identify the content as an image. Additionally, it’s good practice to use proper capitalization and punctuation in alt text descriptions to ensure smooth narration.
Purpose of Alt Text
Alt text has multiple purposes, from SEO to accessibility.
Accessibility for Visually Impaired Users
The primary purpose of alt text is to enhance accessibility for visually impaired users. Alt text, or alternative text, is a brief description of an image added to a web page or a social media post. This text-based representation of visual content is crucial for individuals with visual impairments who rely on screen reader technology.
These users benefit from alt text as it is read aloud, providing an accurate and clear understanding of the image’s content or purpose. By including relevant alt text, developers and content creators can ensure their visual content is perceivable and useful to all users, regardless of their visual abilities.
SEO Benefits
In addition to improving accessibility, an alt tag also plays a vital role in SEO. Search engine bots, including Google, use alt text to understand the content and context of images within a web page. Since search engines cannot visually analyze images, alt text serves as an essential tool for bots to index and rank the visual content. This results in better indexing and increased visibility of websites on search engine results pages (SERPs).
By incorporating relevant and descriptive alt text, content creators can optimize their visual content for SEO purposes, enhancing their website’s overall search engine performance. This can drive more organic traffic to their site and improve overall user experience.
Implementing Alt Text in HTML
Using alt text in HTML is essential for ensuring your images are accessible to a wider audience, particularly those who rely on automatic readers. This section discusses how to implement alt text in your HTML content effectively.
The alt attribute is an HTML attribute that describes an image as text. It should be placed within the <img> element alongside the src attribute, which specifies the image’s source file.
The alt text is not visible on the page, but screen readers will read it aloud for visually impaired users. Moreover, algorithms use it to better understand the content of the image, improving your web page’s SEO.
To implement an alt tag in HTML, you should add the alt attribute inside the <img> tag, like this:
<img src="example-image.jpg" alt="A brief description of the image">
When writing alt text, ensure it is:
- Descriptive and accurate: Provide a clear and concise description of the image, focusing on its purpose or content.
- Relevant and brief: Keep the alt text relevant to the image and avoid lengthy descriptions.
- Avoiding redundancy: Do not repeat the same information found in the surrounding text or headings.
Here are some examples of effective alt text:
- Good: <img src=”puppy.jpg” alt=”A smiling golden retriever puppy”>
- Bad: <img src=”puppy.jpg” alt=”Image of a dog”> (too vague)
It is important to note that when an image is used for purely decorative images for decorative purposes and does not convey vital information, you can use empty alt attribute like this:
<img src="decorative-image.jpg" alt="">
Types of Images
When it comes to web design and accessibility, understanding different types of images is crucial in providing effective alternative text.
Decorative Images
Decorative images are primarily used for visual appeal and do not convey important information. Examples of decorative images include background images, borders, and design elements like icons or graphics. T
hese images do not require a detailed description in alt text since they serve no functional purpose. Instead, the alt text for decorative images can be kept minimal, or you can use empty alt text (alt=””) to reduce redundancy for each screen reader user.
Informative Images
Informative images convey essential information or meaning to the reader. Examples of informative images are photographs, drawings, and illustrations that supplement the content of a web page. Charts and graphs also fall under this category, as they often display data or complex information visually.
Alt text for informative images should be descriptive and concisely explain the image’s content. For more complex images such as charts, consider providing a brief summary of the data in the alt text, and place a more detailed description in the surrounding text or an accompanying caption.
Functional Images
Functional images have a specific purpose or action, such as buttons, clickable icons, or links. These images require alt text that clearly describes the intended function. For example, if an icon represents a “download” button, the alt text should be “download” or “download button.”
Best Practices for Alt Text
Follow these best practices when writing alt text.
Context Relevance
When writing alt text, it is crucial to ensure that the description is relevant to the context of the image. The purpose of good alt text is to provide context for screen readers and search algorithms. Consider the setting, emotions on people’s faces, colors, or relative sizes to effectively convey essential elements of the image.
Descriptive and Concise
The alt text should be sufficiently descriptive to allow users to visualize the image without going into excessive detail. A sentence or two with carefully chosen words will suffice most of the time. The goal is to communicate a reasonably accurate version of the image without overloading the reader with information.
Avoid Keyword Stuffing
Avoid using alt text to stuff keywords irrelevant to the image. While it’s essential to include contextually relevant keywords, avoid spammy or unnatural use. Focus on creating accurate, helpful, and natural-sounding alt text that benefits screen reader users and search engines alike.
File Names and Alt Attributes
The file name of an image can also contribute to its overall impact on SEO and accessibility. It’s a good idea to use descriptive, meaningful image file name and names for your images, instead of relying solely on alt text for context.
When adding the alt attribute to your image tags, ensure it provides a clear description of the image’s content that effectively conveys its purpose. This will help screen reader users understand what the image displays and improve the crawling and ranking of your website by algorithms.
Alt Text in Content Management Systems
Content management systems (CMS) are widely used for creating and managing digital content, and one crucial aspect of managing images in a CMS is using alt text effectively. CMS platforms like WordPress make adding and editing alt text simple when you’re uploading or using images on your website.
In WordPress, for instance, it is easy to include alt text when adding images to your content. When you upload an image from your computer or choose an existing image from your Media Library, you’ll notice a field labeled “Alt Text” where you can add a brief, descriptive text for that image.
Always ensure that the alt text you provide is accurate, concise, and relevant to the content that surrounds the image. This helps automatic readers convey the appropriate message to visually impaired users and assists algorithms in understanding your site’s content.
Some other content management systems may have different processes to either add alt or edit the alt text, but in most cases, the process is straightforward and easily accessible.
Using alt text appropriately in a content management system not only improves accessibility for visually impaired users but also enhances your site’s SEO, making it more visible and accessible to a wider audience.
By following best practices for writing alt text and incorporating them effectively within your chosen CMS, you can create a more inclusive and optimized digital experience for your users.
Optimizing Images for Search Engines
Effective image SEO is crucial for improving website visibility in algorithms. One significant aspect of image SEO is proper use of alt text.
Conducting keyword research is an invaluable step in optimizing images. Knowing the right keywords to target ensures the alt text effectively conveys the image’s content and matches queries relevant to the topic. Incorporating these keywords adds context, helping search engine crawlers better understand and index the images.
Google Images is a powerful platform where image search results are displayed prominently. Properly optimized alt text improves the chances of the images from your website appearing in top search results. This, in turn, increases your website’s visibility and traffic.
Image SEO involves more than just alt text; it also entails optimizing image file names, sizes, and formats. Descriptive file names and smaller file sizes contribute to overall website performance and impact search engine rankings.
Search engine crawlers are responsible for indexing web pages and their content. Proper alt text and other image optimizations ensure crawlers can index your images accurately, boosting your website’s rankings. Providing valuable and relevant information through alt text allows crawlers to index images for image search results based on user queries.
Images on Social Media Platforms
Social media platforms, such as Twitter, play a significant role in how people share and access visual content. Images are a powerful tool, engaging users and conveying information in a visually appealing way. However, people with visual impairments may not fully experience or understand these visuals without assistance. This is where alternative text, or alt text, comes in.
By including alt text in social media posts featuring images, content can become more accessible to a wider audience, including those with visual impairments.
Major social media platforms have incorporated alt text features into their posting options. For instance, Twitter allows users to add alt text to image captions while composing a tweet, ensuring the content reaches everyone, regardless of their visual abilities.
To write alt text, consider the following best practices:
- Keep it concise and relevant to the image
- Describe the image’s purpose and content in a clear and neutral tone
- Avoid including redundant information that is already present in the text accompanying the image
By adopting these practices, content creators can make their social media posts more inclusive, ensuring that everyone has an opportunity to engage with images shared across various social media platforms.
Advanced HTML Features and Alt Text
Here’s a look at how to use alt text with advanced HTML features.
Image Maps
Image maps are a means to create clickable areas on an image in HTML, allowing users to navigate to specific sections on a web page. These maps can have multiple shapes like rectangles, circles, and polygons with an associated URL.
Using alt text for each clickable area within an image map is essential, providing a clear and concise description of the destination link. This makes it accessible for visually impaired screen reader users.
Here’s an example:
<img src="example_map.png" alt="Image Map Example" usemap="#map1" />
<map name="map1">
<area shape="rect" coords="0,0,50,50" href="section1.html" alt="Section 1" />
<area shape="circle" coords="100,100,50" href="section2.html" alt="Section 2" />
</map>
Image Height and Width Attributes
Specifying the height and width attributes of an image in HTML helps browsers allocate appropriate space for the image on the page, ensuring smooth loading and reducing layout shifting.
Although these attributes don’t directly impact alt text, maintaining proper formatting and organization of the image within the web page enhances user experience for visually impaired users, as it affects the order and synchronization of a screen reader’s output. Proper alt text should still be used to describe the image’s content and purpose. For example:
<img src="example_image.jpg" alt="Sample Image" width="300" height="200" />
By using advanced HTML features, web developers can create accessible and user-friendly web pages. Employing relevant alt text for image maps and images with specified height and width attributes ensures that visually impaired users can access the content and better understand the purpose and functionality of the images on the website.
Final Thoughts
Learning how to write alt text is essential. By incorporating clear, concise, and contextually relevant alt text for images on websites and apps, you can ensure you will reach a wider audience and maintain an inclusive online environment.
Proper alt text implementation benefits individuals relying on screen readers and improves SEO. Search engines like Google or Bing use these descriptions to index content effectively, making it more easily discoverable for users.
Prioritizing the use of alt text elevates the overall user experience for those with visual impairments and optimizes content for search engines. By adhering to best practices and considering the needs of all users, content creators can contribute to a more accessible and inclusive digital world.
Raymond Li is known for his deep understanding of SEO and ability to develop successful client campaigns. His technical expertise and creativity have helped businesses of all sizes to improve their organic search presence. Ray enjoys playing ultimate frisbee and exploring the local cuisine when not dominating the SERPs for a wide array of juicy keywords.