Alt tags help describe the appearance and function of each image that you upload. As you upload an image from your iPhones, stockphoto or other source, you’ll be presented with fields where you can provide a description, caption and alt tag. In general, if there’s a field, fill it out—it’s an opportunity to use your keywords and reiterate the name of your business.
Start by labeling your images
Rather than the default numbers that are automatically attributed to your images, start relabeling them with brief descriptions. My favorite naming convention is to label the image with the name of your company, underscore, brief image description, such as FordMotorCo_2017redSUV.
Why is alt text important?
Never forget that your audience will be reading your blog, post or website on a wide range of devices and sometimes images don’t load. In those cases, alt tags will be displayed to show readers what they would have been viewing. Those who are visually impaired, by using screen readers, will be able to read an alt attribute to better understand the intent of an on-page image.
Image SEO. Alt tags provide better image context/descriptions to search engine crawlers, helping them to index an image properly.
How to write good alt text
Describe the image as specifically as possible.Alt text should provide text explanations of images for those users who are unable to see them.
Keep it (relatively) short.The most popular screen readers cut off alt text at around 125 characters, so it’s advisable to keep it to that character count or fewer.
Use your keywords Alt text provides another opportunity to include your target keyword on a page, and another opportunity to signal search engines that your page is highly relevant to a particular search query.
Avoid keyword stuffing. Google won’t dock you points for poorly written alt text, but you’ll be in trouble if you use your alt text as an opportunity to stuff as many relevant keywords as you can think of into it. Aim for description and context. Be smart. Remember that just as good content has become nonnegotiable, so are good alt tags.
Don’t include “image of,” “picture of,” etc. in your alt text. It’s already assumed your alt text is referring to an image, so there’s no need to specify it.
Don’t neglect form buttons. If a form on your website uses an image as its “submit” button, give it an alt tag. Nothing surprising here—the button is a graphic and deserves an image label and alt tag in the same way that all of your other images do.