One of the first rules of web copywriting is to use plain English, to give every reader the best chance of understanding your content. Your website is available to the entire world and will have visitors who have a first language different to your own. Don’t forget, however, that native speakers also have differing reading and writing abilities.
Writing in a simple, clear style benefits all users; it makes your website easier to read and understand (communicating your messages more effectively). Concise copy fulfils accessibility requirements for both people and search engines, making your website also easier to find.
Reading ability will vary within your own audience
The W3C’s WCAG 2.0 has a reading level criterion that says if the ‘text requires reading ability more advanced than the lower secondary education level’, a version that is not more advanced should also available.
This caters for ‘people with reading disabilities [which may include highly educated members of the intended audience] while also allowing authors to publish difficult or complex web content’.