Languages have two general levels of usage: a correct level and an incorrect level

Today I want to talk about levels of language usage. You probably have noticed that people express similar ideas in different ways, depending on the situation they are in. This is very natural. All languages have two general, broad categories, or levels of usage: a formal level and an informal level. English is no exception. I’m not talking about correct and incorrect English. What I’m talking about are two levels of correct English. The difference in these two levels is the situation in which you use a particular level. Formal language is the kind of language you find in textbooks, reference books such as encyclopedias, and in business letters. For example, a letter to a university would be in formal style. You would also use formal English in compositions and essays that you write in school. People usually use formal English when they give classroom lectures or speeches and at ceremonies such as graduations. We also tend to use formal language in conversations with persons we don’t know well or with people we have a formal relationship with, such as professors, bosses, doctors, friends of our parents’, strangers, etc. Informal language is used in conversations with colleagues, family and friends, and when we write personal notes or letters to close friends, as well as in diaries, etc.
    Formal language is different from informal language in several ways. However, today I’m going to talk only about a couple of ways. First of all, formal language tends to be more polite. Interestingly, it usually takes more words to be polite. For example, I might say to a friend or family member, "Close the door, please", but to a stranger or someone in authority I probably would say "Would you mind closing the door?" or "Excuse me, could you please close the door?" Using words like "could" and "would" makes my request sound more polite, but also more formal.
    Another difference between formal and informal language is some of the vocabulary. There are some words and phrases that belong in formal language and others that are informal. Let me give you a couple of examples of what I mean. Let’s say "I’m just crazy about soccer!" But if I were talking to my supervisor or a friend of my parents’, I would probably say "I really enjoy soccer" or "I like soccer very much". Let’s say I’m telling someone some news I heard about the police arresting a criminal. To my friend I might say "The cops bagged the crook". To my parents’ friend I might say "The police arrested the thief".
    Although the line between formal and informal language is not always clear and although people are probably less formal today than in the past, it is useful to be aware that these two levels, or categories, do exist. The best way for a non-native speaker of English to learn the difference is to observe the different ways English speakers speak or write in different situations. Television newscasters, your college professors in class, your doctors in their offices, ere, will usually speak rather formally. However, your classmates, teammates, family members, friends, etc. will generally speak in an informal fashion. The difference can be learned over time by observing and interacting with native speakers.