technical language
   jargon
   legal language
   acronyms (e.g. OLC)
   English idioms
   language that shows class, cultural or gender bias
   use of more than one language

Why?
Technical language, legal language and jargon all exclude readers who are not familiar with the terms. You can usually replace them with common language. If technical terms and legal language must be used, define them in the text or in a glossary.

Acronyms are a special form of jargon — they assume everyone knows the organization that the letters refer to. The first time an acronym is used it should appear with the words it stands for. If it is used frequently, or is commonly known, it can be used alone in the rest of the text.

English idioms and biased language also excludes people — women, poor people, people from other cultures. This language gives the message that these groups are not important enough to pay attention to. It suggests that the material is not for them. English idioms can be particularly confusing. Although they use common words and phrases, idioms always have a more complex meaning, for example — give someone a hand, shake a leg.

More than one language in the text can be confusing because a new reader may not distinguish between the languages, but try to read the whole text.

Section Four gives some simple alternatives for commonly-used complex language.