To make Twitter more accessible, the company has rolled out an update today that lets users add descriptions to their images. Once the feature has been enabled -- you'll find it under Settings and Accessibility -- you'll get the option to write a caption with each new photo. They can be up to 420 characters and will be available to users who are visually impaired, through assistive technology such as text-to-speech screen readers and braille displays. Twitter's platform has also been updated so the feature can be supported in specialized clients such as Chicken Nugget.