You may never have seen the term Alt Text, it is alternative text and is in the settings of pictures. For those who cannot see the pictures, if the picture does not load or if they use a text to speech tool to hear the webpage, knowing what the image is might be useful.
If the image is there as decoration and does not have any value to information then you can leave the Alt Text blank or enter text to show that it was a decorative picture.
If the picture or graphic is really important, such as a graph with the number of people who you have helped who would say your service/product is wonderful, then it is important to put in Alt Text.
Remember when entering text that the person probably cannot see the image or if they can, they may not be able to see the detail of it. The Alt Text information needs to be descriptive enough that the image does not need to be there.
To make it easier, image that you cannot see the site at all, what information could someone tell you that would explain the image?
You can add Alt text to images in WordPress but also in other programs like Microsoft Word. This means that if you create a report and someone receives it and uses the text to speech feature they would be able to hear about the images in the document.