What is a non-digital attribute

ALT attributes

An ALT attribute or ALT tag is text that describes a graphic. The abbreviation "ALT" stands for "alternative". The ALT attribute is stored on image files on a website. If an image cannot be displayed for certain reasons, the text of the stored ALT attribute appears. It becomes the alternate text. Search engines use this attribute in order to recognize the image content, since image files can usually not be read out directly. For visually impaired users, the ALT attribute contributes to accessibility. You can read web pages to you with a screen reader. The ALT tags are also used here.

The ALT attribute looks like this:

<img src="verzeichnis/abbildung.jpg" alt="Das ist eine sinnvolle Bildbeschreibung">

How it works [edit]

The ALT attributes appear on the screen instead of images and graphics that cannot be displayed. The attributes are not visible when websites are used conventionally. ALT attributes can only be seen when calling up the source text of a website or with the appropriate tools. If the attribute is correctly integrated, it describes the image content precisely and in a few terms. In the case of graphics with text, this text should also be included in the ALT attributes. All other images are given a corresponding description that is as useful as possible for Internet users and that gives search engines an indication of the content of the image.

On the user side, this has the advantage that a concrete description of the image is available even without an image. From the point of view of search engines, the same applies: The Googlebot cannot yet “read” the image file. He needs additional information to identify the picture content. It also makes sense to provide alternative texts under the keyword “barrier-free Internet”: This way, visually impaired Internet users can also have the text of the ALT attribute read out by a reading program. The images are thus “visible” acoustically to visually impaired people.

Reasons for not displaying images [edit]

The reasons for an image not being displayed can be varied. Browser is out of date: Different types of out of date browsers cannot interpret certain image files. Tracking protection: Some browsers such as Internet Explorer have special tracking protection. If this is activated, some images will not be displayed. Image display is deactivated: Browsers such as Mozilla Firefox have the option of not displaying image graphics. Broken link to the image file: If an image cannot be displayed by the browser, a broken URL to the image resource may be responsible. Such errors can occur, for example, if an image directory on the server has been renamed or moved. Internet Explorer 7 displayed the ALT attribute as a tooltip. This is why it was often incorrectly used as a tooltip in other browsers. However, this is the task of the title tag, assuming valid HTML. To avoid the ALT attribute being displayed as a tooltip, the longdesc attribute was used. However, with the newer generation of browsers this attribute becomes superfluous.

Importance for SEO

In search engine optimization, the ALT tag plays an important role on the one hand for the user and on the other hand as content for the Googlebot. If the ALT attribute is displayed when there is no browser support, the usability of the website is not restricted. The alternative text allows the user to see what should be presented. For search engines, ALT tags provide important information about the image content and the overall context of the website.

Optimization of ALT tags [edit]

In general, it is recommended to store the main keyword of the website in question in the ALT attribute in order to improve the keyword focus. At the same time, the text should provide a precise and concise description of the image content. However, the ALT attribute should not be used for keyword stuffing, as Google and other search engines rate this technique as spam. The use of keywords in the ALT tag is important to improve the rankings in the image search. The optimization of ALT attributes is therefore part of image SEO and contributes to the sustainable OnPage optimization of websites.


The operator of an info blog about cats incorporates a new picture of a very special four-legged friend. The URL of the page is: Meinekatzseite.de/katzen-mit-großen-ohren

He would then embed the picture in his blog as follows:

<img src="/katze-mit-grossen-ohren.jpg" alt="Junge Savannah Hauskatze bräunlich getigert mit sehr großen Ohren und braungruenen Augen">

In interaction with the file name, the keyword focus can be strengthened with the content of the URL. In the context of image SEO, the file size should not be underestimated. It also plays a role in the loading time and thus the performance of the page.

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Web links [edit]