What is Alt tag ?

[BritneaWilson]

ALT Tags are invisible descriptions of images which are read aloud to blind users on a screen reader. Adding ALT text allows authors to include images, but still provide the content in an alternative text based format.

[Sophiacalvin]

For the use of alt features in Wikipedia, see Wikipedia:Substitute text for images. The alt feature is used in HTML and XHTML documents to identify substitute text (alt text) that is to be delivered when the factor to which it is used cannot be performed.

[austen]

Alt tags are used for optimizing your imageIf we use keywords in alt tags then search will identify your image.Its sole purpose is to increase the visibility of your images.
When particular key word is searched then your image will appear in result page and if visitor click the image your site will be displayed..

[rvtrainingchd]

Alt text is meant to be an alternative information source for those people who have chosen to disable images in their browsers and those user agents that are simply unable to see the images. It should describe what the image is about and get those visitors interested to see it.

[nilam-shah]

An HTML attribute specified in the IMG tag to provide alternate text when an image on a Web page cannot be displayed.

[christopher12]

Alt tag is use for understand of image.