Final answer:
The subject of this question is English and it discusses the difference between informal and formal English.
Step-by-step explanation:
The subject of this question is English, specifically the use of informal and formal English. Informal English is the language of everyday speech, characterized by the use of contractions, slang, and popular expressions. Formal English, on the other hand, is more standard and grammatically correct. The question discusses the differences between these two varieties of English and provides examples of how they are used in different contexts.