Alternative text, or "Alt Text," serves as a text fallback for your images in the event that they cannot be loaded.
Any of the photos on your website that are embedded on the page can easily have alt text supplied with WordPress. On the right side, you can input custom text after selecting your image from the Media Library.
Alt text should ideally just explain what the image is about. A dog sitting on a bench, for example, would have the text "a dog sitting on a bench" next to it. WordPress will default to using the name of the picture file in cases when custom text is not specified. DSC2035.jpg isn't very helpful, but it might be if you called your file after the image's subject!
Alt text is significant for search engines as well as serving as a helpful description of an image in the event that it hasn't loaded. A search engine bot will be able to identify an image's topic from its alt text and index it accordingly. This will improve both the individual pages and posts on your website as well as its overall SEO.
Last but not least, screen readers are tremendously helpful for people who are blind or visually challenged. Screen Readers are add-ons for browsers that scan a page's content and read it aloud to the user. It will also be able to describe any images on the website that have alternate text.
You might greatly enhance your website by simply adding a few descriptive text to your photographs.