Starting from a series of examples from the English language, the paper deals with the development of modern slang, this picturesque “way of expression” so widely used in our ever developing fields of activity. Generally speaking, slang can be classified, according to the sphere of usage, in general slang (words that are not specific for any social or professional group) and special slang (words peculiar for some such groups as teenagers, university students). There is also a very interesting linguistic phenomenon known as rhyming slang, particularly common in British English, in fact a secret argot depending on rhyme as a device, which originated in the Cockney underworld of the 19th century. Speakers of English everywhere seem to have become more liberal, admitting more and more slang into their everyday speech, radio and TV programs, words which not long ago were considered either vulgar in the extreme or even taboo terms. Slang terms cannot be distinguished from other words by sound or meaning, all being once cant, jargon, argot or dialect, and changing from period to period as the language develops gradually. Having a primarily spoken usage, which has nevertheless conserved several centuries-old terms, slang is best recorded by employing direct sources. Despite being associated with various subcultures, slang is today socially acceptable, as it adds a new dimension to the language, enhancing the expressiveness of the discourse when appropriately employed.