What does readability typically measure?

Readability primarily measures how easy or difficult it is to read a piece of text, which is often correlated with the education level required to understand that text. This involves evaluating factors such as sentence length, word complexity, and overall structure, which together help indicate the audience's required reading ability. A text that is written in simpler language and shorter sentences is generally more accessible and can be understood by a wider audience with varying educational backgrounds.

Understanding readability is crucial for creating accessible documents, as it ensures that the intended audience is able to comprehend the material without undue difficulty. This aligns closely with the goals of accessibility, which strive to remove barriers for readers of different skill levels.

The other options, while relevant to aspects of document creation or typography, do not directly address the core concept of readability in the same way. For instance, the length of a document is more about the overall size rather than the ease of understanding it, while the complexity of language pertains to specific word choices rather than the overall readability score. Visual aspects of text, such as font size and color, while important for accessibility, also do not directly measure readability as it relates to comprehension.