Cockney is the working-class dialect of London, and one of the most noticeable of all the regional accents of England. The sounds are very different from standard English, and it has a number of conspicuous grammatical features.

Londoners use a wide variety of accents, from Cockney through intermediate forms typical of south-eastern England, to Received Pronunciation (RP). Formerly RP was the variety used by the educated minority heard over the airwaves, but these days the intermediate form known as Estuary English is also widely used, and this has some but not all the features of Cockney.

In the nineteenth century one feature of Cockney was the use of V for W: Dickens's Sam Weller in Pickwick Papers is the best-known example, calling himself Veller. This alternation persisted (at least in cartoons) till about 1900, but there is no trace of it now.

One striking and unique feature of Cockney is the change of TH to F and V. In what follows I'm going to give phonetic transcriptions in the SAMPA system as well as ad-hoc respellings. So feather is pronounced [fev@] fevver, and bother is pronounced [bQv@] bovver. At the beginning of a word voiceless [T] becomes [f], as in thick [fIk] fick. The voiced sound [D] of this usually becomes [d], so this and that is pronounced dis an da', but it may also be [v], or be omitted entirely.

Another striking difference from standard English is the dropping of H. This is not a purely Cockney thing: all the regional dialects of southern England lost H some centuries ago. But standard English has resisted it, and teachers and grammarians used to condemn it as one of the most serious faults of sub-standard English. Normally features arising in London speech spread into educated or 'good' English within a few generations, but this has not happened with H-dropping. It doesn't occur with the intermediate Estuary English either.

A third big consonant difference is the use of the glottal stop in place of T. The sound [t] is kept when it's followed by a stressed vowel, as in tea or return, but the glottal [?] is used in most other environments, as in water [wOU?@] wo'a and get it [ge? I?] ge' i'. This sound change is used in Estuary English, and though glottalling has been condemned as 'ugly' by a few, it can be heard on the lips of people in the highest places.

Another consonant change shared with Estuary is the change of L at the end of a syllable to something like W, or some kind of rounded vowel. So ball [bOo] baww and fill [fIo] fiww. In combination with the previous change this gives filter [fIo?@] fiw'a and bottle [bQ?o] bo'w.

S generally becomes an SH sound before the afficates CH and TR, as in stew [StS@u] shchoo and straw [StrO@] shchraw.

With vowels there has been a systematic shift of most of the long vowels and diphthongs. Cockney has taken this the furthest, though Estuary has gone part-way in the shifts and Australian has undergone rather similar changes. In fact earlier forms of Cockney seem to have been a significant source of the Australian accent. The [eI] vowel of lace has moved down to [6I] to make it sound rather like standard lice, while that vowel has moved further back to become more like that of choice. The vowel [@U] or [oU] of goat has shifted down to [6U], with the first part more like gah; and the [aU] of words like mouth is variable but with a first part more like that of man, or may be entirely the same vowel, giving [m{:f] maaf.

In describing Cockney as a dialect, not just an accent, I mean there are significant grammatical differences. These are not exclusive to Cockney, and usually occur in other south-eastern varieties, but they are not standard English, and most of them are not used in the neo-standard Estuary English. These include: spread negation, as in I ain't done nothing [6I en? dan nafINk]; a different use of past tenses, as in I seen it, I done it; and demonstratives like them books.

The best-known vocabulary aspect of the dialect is the humorous word replacement known as Cockney rhyming slang.