Yes, most search engines, including Google, read images by the image file name and Alt tags. They look for a particular tag called “ALT tag” and “Image names” when indexing your Web page. For many sites, particularly sites heavy on images, ALT text is one of the few elements available for search engines to index. ALT tags are a required element for standards-based HTML coding.
Why should we use ALT tags?
While programming, it is important to think about people using browsers designed for people with visual, hearing or other impairments. Others who view your site may choose not to download any of the images. The ALT tag gives you the capability to convey your message in either case.
Alternative text is especially useful in the following situations:
• Visitors with low bandwidth connections, who may opt not to load graphics can read your alt tags and know the image content you have on that page.
• Visitors using handheld devices can see your alt tags before loading heavy images.
• Visitors with disabilities or visual/hearing impairments can read the alt tags.
How should we use ALT tags?
ALT tags must briefly describe the image and they should have keywords for relevancy.