Access: [1.1.1.1]: <img> missing 'alt' text (Priority 1)

Cause:

All images -- including transparent GIFs -- must have "alt" text (short for "alternate"). Alternate text describes the information in the image, which is useful for three important purposes:

Some user agents render the alt text as a tool-tip: the little yellow box that pops up when you hold your mouse cursor over the image.

Alternate text should be concise (i.e. 10-12 words maximum). For transparent images and spacers, use alt="" (NULL), alt=" " (spaces are acceptable), or alt="blank". Any words depicted in the image should also appear in the "alt" text description.

Example:

Good
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en">
<head>
<title>aert1.0/1.1.1</title>
</head>
<body>
<img src="banana.jpg">
</body>
</html>
Good
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en">
<head>
<title>aert1.0/1.1.1</title>
</head>
<body>
<img src="banana.jpg" alt="A picture of a banana.">
</body>
</html>

Solution:

Add a description of the image as an alt attribute.

References: