11.5 Alt text and captions

Alt text and captions are crucial for making web content accessible and inclusive. They provide textual descriptions of images, aiding users with visual impairments and improving SEO. This topic explores the benefits, best practices, and implementation of alt text and captions in various contexts.

Effective alt text and captions enhance user experience, comply with accessibility guidelines, and support legal requirements. By understanding how to create and implement these elements, web designers and content creators can ensure their digital content is accessible to all users, regardless of their abilities or technology constraints.

Benefits of alt text

• Alt text, short for alternative text, provides a textual description of an image's content and purpose
• Aids in making web content more accessible and inclusive for all users, regardless of their abilities or how they access the web
• Serves as a vital source of information for users who rely on assistive technologies, such as screen readers, to navigate and understand web pages

Accessibility for screen readers

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• Screen readers are assistive technologies that convert text and image descriptions into synthesized speech or braille output
• Alt text enables screen reader users to understand the content and context of images on a webpage
• Without alt text, screen reader users may miss out on important information conveyed through images

Improved SEO

• Search engines, like Google, use alt text to better understand the content and context of images on a webpage
• Including relevant and descriptive alt text can improve a website's search engine rankings and visibility
• Alt text provides an additional opportunity to include target keywords, enhancing the page's relevance for specific search queries

Graceful degradation without images

• In situations where images fail to load due to slow internet connections, browser settings, or other technical issues, alt text provides a fallback
• Alt text ensures that users can still understand the intended message or purpose of the image, even when the visual is not displayed
• Graceful degradation maintains the usability and accessibility of a webpage, regardless of the user's environment or technology constraints

Writing effective alt text

• Effective alt text should be concise, descriptive, and contextually relevant to the image and its purpose within the content
• Alt text should provide enough information to convey the essential meaning of the image without being overly verbose
• Best practices for writing alt text include using clear language, avoiding redundancy, and considering the image's role in the overall content

Describing visual content concisely

• Alt text should briefly describe the most important aspects of an image, focusing on the content and purpose rather than aesthetic details
• Use clear, concise language that conveys the essential information without being overly wordy or complex
• Examples of concise alt text: "Woman hiking on a mountain trail" or "Graph showing quarterly revenue growth"

Avoiding redundancy with captions

• When an image is accompanied by a caption that adequately describes its content, the alt text should not repeat the same information
• In such cases, the alt text can provide additional context or be left empty if the image is purely decorative
• Example: If a caption reads "Sunset over the ocean," the alt text might add context like "Silhouette of a sailboat against an orange sky"

Alt text length considerations

• While there is no strict character limit for alt text, best practices suggest keeping it relatively short and focused
• Screen readers may truncate or pause longer alt text, which can be disruptive for users
• Aim for alt text that is typically around 125 characters or less, while still providing adequate description

Blank alt attributes for decorative images

• For purely decorative images that do not convey meaningful content, the alt attribute should be included but left empty (alt="")
• This signals to screen readers that the image can be safely ignored, reducing cognitive load and improving the user experience
• Examples of decorative images include visual flourishes, borders, or spacers that do not contribute to the page's content

Alt text in HTML

• In HTML, the alt attribute is used to specify alternative text for an image
• The alt attribute is a required attribute for the

  <img>

  tag, and its value should be a concise description of the image
• Proper usage of the alt attribute is essential for creating accessible and SEO-friendly web content

Importance of alt attribute

• The alt attribute ensures that users can understand the content and purpose of an image, even if the image fails to load or the user relies on assistive technologies
• Including alt text is a fundamental aspect of web accessibility and is required for compliance with guidelines such as WCAG (Web Content Accessibility Guidelines)
• Search engines use alt text to index and understand images, which can positively impact a website's search engine rankings

Proper alt attribute syntax

• The alt attribute is added to the

  <img>

  tag, following the src attribute that specifies the image file path
• Example of proper alt attribute syntax:

  <img src="image.jpg" alt="Description of the image">

• The alt text value should be enclosed in double quotes and should not contain any HTML tags or special characters

Empty vs missing alt attributes

• An empty alt attribute (alt="") is used for decorative images that do not convey meaningful content and can be safely ignored by assistive technologies
• A missing alt attribute, where the attribute is omitted entirely, is considered an accessibility error and should be avoided
• Images that are important for understanding the content should always have a descriptive alt text value

Benefits of captions

• Captions provide additional context and information about an image, video, or audio file, enhancing the user experience and accessibility
• While alt text is primarily intended for users who cannot see the visual content, captions benefit all users by offering supplementary details
• Captions can help improve user engagement, comprehension, and overall satisfaction with the content

Additional context beyond alt text

• Captions can provide more detailed information about an image or media file, expanding upon the brief description provided by alt text
• This additional context can include details such as the location, date, or significance of the content, or any relevant background information
• Example: A caption for a photograph might read, "Sunset at Malibu Beach, California, captured during the summer solstice in June 2022"

Improved accessibility for all users

• Captions benefit not only users with visual impairments but also those with cognitive disabilities, language barriers, or learning preferences
• By providing a text alternative to visual content, captions make the information more accessible and easier to comprehend for a wider audience
• Captions are particularly useful for users in sound-sensitive environments or those with hearing impairments when consuming video or audio content

Enhancing user engagement

• Well-written captions can pique users' interest and encourage them to engage more deeply with the content
• Captions can provide additional insights, context, or even a touch of humor, making the content more memorable and shareable
• By offering a more comprehensive and engaging experience, captions can increase user satisfaction and encourage longer visits to a website or application

Writing effective captions

• Effective captions should complement the visual content without being redundant or overly verbose
• Captions should be concise, informative, and styled appropriately to ensure readability and accessibility
• When writing captions, consider the purpose of the content, the target audience, and the overall tone and style of the website or application

Complementing visual content

• Captions should provide additional information that enhances the understanding or appreciation of the visual content
• Avoid simply restating what is already apparent in the image or media file; instead, offer supplementary details or context
• Example: Instead of a caption that reads "A red car," provide more context like "A vintage 1965 Ford Mustang in cherry red, parked outside a retro diner"

Captions vs subtitles

• Captions and subtitles serve different purposes and should not be used interchangeably
• Captions provide additional descriptive information about visual content, while subtitles are a text alternative for the spoken content in a video or audio file
• Subtitles are typically a transcription of the dialogue or narration, often used for translation purposes or to assist users who are deaf or hard of hearing

Optimal caption length and style

• Captions should be concise and easily readable, typically no more than a few sentences in length
• Use clear, simple language and avoid jargon or complex terminology unless necessary for the target audience
• Ensure that the caption text is visually distinct from the surrounding content, using appropriate font size, color, and contrast
• Consider the placement of captions, ensuring they do not obscure important parts of the image or interfere with other text elements

Implementing captions

• Captions can be implemented in various formats and file types, depending on the type of media and the platform or CMS being used
• Proper association of captions with their corresponding media files is essential for accessibility and usability
• Different approaches may be required for implementing captions for audio content versus video content

Caption formats and file types

• Captions can be implemented using various file formats, such as .srt (SubRip Subtitle), .vtt (WebVTT), or .smi (SAMI)
• The choice of file format may depend on the specific requirements of the media player or platform being used
• Some platforms, like YouTube, offer built-in tools for adding and editing captions directly within their interface

Associating captions with media

• To ensure that captions are properly displayed and synchronized with the media content, they must be correctly associated with the corresponding media file
• This can be achieved through the use of HTML5 media elements, such as

  <video>

  and

  <audio>

  , and their child

  <track>

  element
• The

  <track>

  element is used to specify the caption file and its attributes, such as the language and label

Captions for audio vs video

• While the general principles of caption writing and implementation apply to both audio and video content, there are some differences to consider
• For audio content, captions may include speaker identification, sound effects, and other relevant non-speech information
• Video captions may need to be synchronized with the visual content and should be placed in a way that does not obstruct important visual elements
• When creating captions for video, it's essential to consider the timing and pacing of the captions to ensure they are readable and do not overwhelm the viewer

Alt text and captions in CMSs

• Many content management systems (CMSs) offer built-in features or plugins for adding and managing alt text and captions
• These tools can help streamline the process of creating accessible content and ensure consistency across a website or application
• Some CMSs may also offer automated tools for generating alt text or captions, though these should be reviewed and edited by a human for accuracy and context

Inputting alt text in WordPress

• WordPress, one of the most popular CMSs, allows users to add alt text to images through the Media Library or when inserting an image into a post or page
• To add alt text in WordPress, click on an image in the Media Library or within the post/page editor, and fill in the "Alternative Text" field in the attachment details sidebar
• WordPress also provides fields for adding captions and descriptions to images, which can be displayed alongside the image on the front end of the website

Adding captions in popular CMSs

• Other popular CMSs, such as Drupal, Joomla, and Shopify, also offer methods for adding captions to images and media files
• In Drupal, captions can be added using the Media module or through custom fields, depending on the specific configuration of the website
• Joomla allows users to add captions to images through the built-in Image field type or by using third-party extensions
• Shopify provides an "ALT Text" field for images and a "Caption" field for adding descriptive text to be displayed below the image

Automated alt text and caption tools

• Some CMSs and third-party tools offer automated solutions for generating alt text or captions using artificial intelligence (AI) or machine learning (ML) algorithms
• While these tools can be helpful for quickly generating basic descriptions, they should not be relied upon entirely for creating accurate and contextually relevant alt text and captions
• It's important to review and edit automatically generated alt text and captions to ensure they accurately convey the intended message and purpose of the visual content

Legal requirements

• Providing alt text and captions is not only a best practice for accessibility and user experience but also a legal requirement in many jurisdictions
• Failure to comply with accessibility laws and guidelines can result in legal consequences, financial penalties, and damage to a brand's reputation
• Understanding and adhering to the relevant legal requirements for alt text and captions is essential for creating inclusive and compliant digital content

ADA compliance for alt text

• The Americans with Disabilities Act (ADA) requires that all public-facing digital content be accessible to individuals with disabilities, including those who use assistive technologies
• Under the ADA, images must have accurate and descriptive alt text to ensure that users with visual impairments can access and understand the content
• Failure to provide alt text for important images can be considered a violation of the ADA and may result in legal action against the website owner or organization

WCAG guidelines for captions

• The Web Content Accessibility Guidelines (WCAG) provide a set of international standards for creating accessible digital content, including guidelines for captions
• WCAG 2.1 Success Criterion 1.2.2 (Captions - Prerecorded) requires that all prerecorded audio content in synchronized media have captions, with some exceptions for specific situations
• To meet WCAG guidelines, captions must be accurate, synchronized with the audio, and include all relevant non-speech information, such as speaker identification and sound effects

Potential consequences of non-compliance

• Non-compliance with accessibility laws and guidelines can result in a range of consequences, depending on the jurisdiction and the specific circumstances
• Potential consequences may include:
  • Lawsuits and legal action brought by individuals or advocacy groups
  • Financial penalties and fines imposed by regulatory bodies
  • Damage to the brand's reputation and public image
  • Loss of business and revenue due to inaccessible content
• To mitigate these risks, organizations should prioritize accessibility and ensure that all digital content, including images and media files, meets the required standards for alt text and captions