This paper is about different argots used by various groups of people, and will focus on Cockney rhyming slang in particular. Firstly, to be able to comprehend the topic fully, those terms must be explained and defined. Also, in numerous cases it can be seen that people tend to confuse argot with jargon or slang, and in this thesis those terms will be differentiated. The reader will be introduced to argot as a secret language used by different groups to prevent people outside those certain groups from understanding what they are saying. Argot is commonly connected with groups such as criminals, thieves and students, but it is not limited to only those. Most of the words that develop in a certain argot are not a part of standard speech. There are many subtypes of argots that have developed in different countries and out of different needs of people when they needed privacy, but they still wanted to communicate orally. The major part of this paper focuses on Cockney rhyming slang, which is a well-known argot that originated in the East End of London. Cockney rhyming slang phrases are obtained from using an expression or a name that rhymes with a word which is supposed to be replaced, and then using that expression instead of the original word. Numerous expressions have gone from being used by only Cockneys into usage in common language. Also, the creation of new phrases and expressions is no longer restricted to just Cockneys.