Quick definition
Alt text is a written description of an image that screen readers read aloud — it makes visual posts accessible and gives platforms context about the content.
Alt text (alternative text) is a short written description attached to an image — not visible on the post itself, but read aloud by screen readers, shown when an image fails to load, and parsed by software that can’t see pixels. Most major networks let you add custom alt text when you upload an image — Instagram, Facebook, X, LinkedIn, Pinterest, and Mastodon among them — and several generate automatic descriptions when you don’t, usually far worse than what you would write yourself.
The primary reason is access: blind and low-vision users experience your visual content entirely through alt text, and skipping it excludes them from the conversation. There are secondary effects — image descriptions give platforms readable text to understand and index, and accessibility is an explicit community norm in some corners of social: much of Mastodon and fediverse culture expects every image to carry a description. Teams that bolt alt text on after publishing rarely keep it up; teams that write it while preparing posts do.
An auto-generated description might say “Image may contain: person, indoor.” A useful one says: “A barista pours latte art into a white cup; a chalkboard behind her lists the new winter menu.” The second tells a screen-reader user what the post is actually about — including the text inside the image, which software won’t reliably read otherwise. Write for the post’s purpose, not for a forensic inventory of the pixels.
Describe what matters in context, in one to three sentences; transcribe any text that appears in the image; skip “image of” (screen readers already announce that it’s an image); and don’t stuff keywords — alt text is for people first, and no platform publishes a ranking reward for it. Character allowances vary by network (X permits roughly 1,000 characters as of 2026), but good alt text rarely needs more than a couple hundred.
Where SocialKit fits
Scheduling ahead with SocialKit’s content calendar buys you time for the details that get skipped when you post in a rush — accessibility is far easier to keep consistent when posts are prepared in batches instead of fired off live.
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FAQ
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