Uppercase (all caps) text is harder to read. It can also be perceived as 'shouting' online. Firstly, some screen readers read capitalized text letter-by-letter. And this occasionally even occurs when the HTML is in sentence-case and the CSS forces the capitalization.
The use of All Caps can reduce the readability of your text. Usability expert Jakob Nielsen has found that reading on screen can be around 25% slower than reading from paper, and reading All Caps can be a further 10% slower.
When we read, we don't actually look at every letter in a sentence, but actually the shapes of the words. When text is in All Caps, the height of every letter is identical making every word an even rectangular shape, forcing us to read letter-by-letter, reducing our reading speed.
It is good to reconsider using all uppercase text if it is done for design and aesthetic purposes. An exemption to the this rule is if a brand or legal word is strictly specified to be all upper case.
How can I resolve this issue?
Change text so that not all letters are upper case
What topics do this checkpoint affect?
Can you explain how this checkpoint works?
By default the checkpoint examines the entire HTML source code of a page and reports if more than three successive words are in uppercase.