Language is a form of our living. We can express ourselves with the help of it. Language is a soul of every nationality, its saint thing, the dearest treasure. By the level of its development we can judge about the development of the spiritual side of every nation. It has often been difficult for the English learners to choose a suitable word or phrase in a certain situation. It is happening because English is divided into two big groups, formal and informal language. But what parts of the language are defined to be either formal or informal? This question is raised when we need to write a letter to our pen friend, who lives in another country, or to write a formal letter in official business style. In order to omit different linguistic problems and mistakes we need to realize clearly which grammatical structures refer to each of these styles. That is why I have chosen this topic for my future investigation. I have tried to find rare and interesting books dedicated to this topic and I tend to think that they helped me to develop and enlarge my work. My work consists of several parts that have different information directions. In the first part steps of Standard English formation are described. The Eastern Midlands dialect, the dialect of one part of the country, became the national, standard written language for the whole country. The work continues by the analysis of English grammar. It is often been said that English has no grammar, or that, if it has, there are no rules in it. English has indeed very few of the kind of inflections, on the end of nouns and verbs, that play such an important part in the grammar of many other languages. Nor has English grammar a place for gender in nouns. Most English that we learn can be used in a wide range of situations. But we will also hear or see language that is formal or informal, sometimes very formal or very informal. We need to be more careful with this language because it may not be suitable in certain situations. Formal English is more common in writing than speaking. It is found in notices, business letters, and legal English; but we can also hear examples in spoken English. In general, informal language is more common in spoken English than written English. Certain types of language are often informal: - most uses of get are informal; - many phrasal verbs are informal; - many idioms are informal Vague language and slang are also examples of informal English. Vague means ‘not clear or precise or exact’. Slang is a form of very informal language. It includes words used by particular groups of people (e.g. some young people may refer to ‘drugs’ as dope), and also words which many people think are impolite and unacceptable in most situations. We should not use these words, but some of them are quite common. Study of the informal language has a deeper analysis in my work, because this type of language is used by the great amount of people. The aim of my work was to show the possibilities of English language usage and to create a system of our knowledge of English language. Language is an eternal thing, which unites all people around the world.