2.1 Formal and informal In terms of formality,English words can be categorized as formal and informal. Formal diction is used in the standard discourse suitable for academic or business writing. Informal diction is more conversational and reflects a more casual relationship between writer and audience.2.1 Formal and informal In terms of formality, English words can be categorized as formal and informal. Formal diction is used in the standard discourse suitable for academic or business writing. Informal diction is more conversational and reflects a more casual relationship between writer and audience