What is the Image Alt Text attribute and how do I use it properly?
To a computer, an image exists as code. When rendered in a web browser, a human is able to discern the content of the image which conveys meaning visually. To a machine, the image is still a bunch of ones and zeros even when rendered.
1) Being as this is the case, the search engine’s algorithms are not capable of determining if an image on a Plumber’s website is of something pertinent, such as a business logo, a photo of a pipe or wrench, or a before / after shot of a job well done, or something completely unrelated, such as a photo of a ketchup Popsicle held by a woman in white gloves. For the search engines to provide image search capabilities, they have to have some idea as to the content of an image. This is gathered based upon surrounding content on the page, the content present on the domain itself, the name of the image file itself, and any ALT text, or other descriptive text, which may be present within the image’s HTML call.
2) In addition to the above, when a visually impaired individual loads a website, they may not be able to see an image or read the text on the screen. In this instance the individual uses what is called screen-reader software. This software reads off the content of the displayed website’s page to the user. When an image is encountered by a screen reader, the alt text (and in some cases other set attributes) are read off to the user, allowing them to utilize the website more completely.
3) Furthermore, if something occurs with the image or its reference URL which causes it to not be displayed, the text which has been set within the Alt attribute is displayed in its place.
Although you may view 2 and 3 as ancillary points, they are assuredly not. The usability of a website is an integral part of a search engine’s (Google’s) ranking algorithm. So a website which does not offer usability to the visually disabled, or fallback support for an image which fails to load, is considered less complete and useful than one that does–all other things being equal.
Is setting an Image’s Alt Text good for my website’s SEO?
The short answer is yes, in most cases it will be. The long answer is that setting the Alt text for an image will increase the amount of machine-readable content on your website’s pages which, in most cases, will serve to improve your website’s relevance as determined by the search engines. And when a search engine crawls your content and attempts to determine its usability score, it will be recorded as being more user friendly which is always a benefit.
Image Alt Text Note: It’s important to keep in mind that spam rules still apply to Alt text. If you simply insert your targeted keyword for each image on a page, you will likely experience a negative result with regard to your rankings in the SERPs. As a rule of thumb you should keep in mind the purpose of the Alt text: to describe the image to someone whom cannot see it. If this description happens to include keywords, or as I like to recommend, long-tail keywords, naturally, all the better. Oh, and the Alt attributes should be unique for each image on a page as well.
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