There are multiple Australian accents, but thought of as a single accent by the world at large. Here we go, cobber:
Broad: Picture (so to speak) the fair dinkum (honest-to-god), prawn-barbieing (we don't call them shrimp!), dingo-complaining, ute-driving, bushwacking Australian accent of Steve Irwin and Paul Hogan, as well as the former Prime Minister, Julia Gillard. It's not nearly the most common accent and never was, but the country variation is pretty much the only accent recognised by anyone else. Sometimes called Ocker or Strine (named after a rough pronunciation of "Australian" filtered through the accent). Most commonly observed north of Sydney, and in less populated areas of the country (read: away from the southeast quadrant).
The mental image should be Up to Eleven by this point, but if they're from the Northern Territory, turn that Eleven Up to Eleven. Often peppered with more Australianisms than the other accents and not usually spoken by the younger people of Australia. Comes in two varieties: the country variation, which is the most famous Australian accent of all, and the city variation, which is fairly similar but has different vernacularisms. If you speak the city variant, you'll probably be ridiculed for being lower-class; if you speak the country variant, you'll be considered a bumpkin/hick.
General: Less so than Broad, but still recognizably Australian. Often uses less Australian idioms and words and more American or British ones. As the name "General" suggests, this is the most common type of Australian accent. The accent of Cate Blanchett or Nicole Kidman. (Also the accent of Maggie in the movie of Transformers.)
Cultivated: Geoffrey Rush and Hugo Weaving speak with this accent. Also the "There is no spoon" Kid in the first Matrix film speaks in a pronounced Sydney accent.
Screen And Television: The accent of non-Australians attempting the accent and much more oddly the accent often assumed by Australians playing Australians. Combines an exaggerated take of the Broad accent (see above) with a touch of Mary Poppins cockney on occasion.
When Americans attempt to imitate an Australian accent their two most frequent mistakes are the overuse of Cockney (which, to be fair, gets them half-way there) and pronouncing the 'r' at the end of words (most American accents are 'rhotic', most British and Commonwealth are not). When Britons give it a go they're often closer to the mark, but their two most frequent mistakes are the overuse of South African/Boer (which isn't a good 'in' to the accent, due to key differences in pronunciation) and pronouncing their vowels without the requisite nasally-ness. Both often pronounce Australian place-names incorrectly when making phonetic guesses based on spelling. As one of the examples below states, Australians pronounce "Melbourne" as "MELbn" rather than "MelBORN" (as in the birth of a baby) despite the fact that the spelling suggests that it should be the latter.
Indigenous Australian: Not one accent but many. Because there are literally hundreds of different Indigenous Australian languages, Australia's first peoples speak English with a variety of different accents, depending on their ethnicity. If they were not brought up speaking an indigenous language they may also have one of the other 'mainstream' accents you'll read about on this page. It's good to remember that some Aboriginal people speak "Aboriginal English" as their first language, which is a blend of Standard Australian English and their local traditional language/s. It is a recognised English dialect, on equal footing with Standard Australian English (which is the language kids are expected to use at school).
Common Quirks of Australian English
In general, younger Australians will use less stereotypical Aussie slang than older generations, and if they do so it'll often be mockingly. Slang changes over time, as it does everywhere else. Our long national project of shortening even the briefest names to one syllable and an '-o', however, continues unabated (for those at home: when the syllable-and-'oh' combination is phonetically displeasing (Jerry to 'Jerr-o'), why not try replacing the '-o' with a '-zza' ('Jezza')? It never fails!)
If it does fail, try -sy. Usually the first done for names that end with an S. Eg, "Gatesy" for the surname Gates. If the "y" is already there (eg, "Kathy")... remove it!
Although Australians have invented a lot of original words and idioms, and adopted (read: stolen) a rich set of indigenous placenames and a sprinkling of other indigenous terms, we share some terms with the USA. For instance, we call vegetables of the species Cucurbita pepo "zucchinis" rather than "courgettes". This is because these words were in common usage in England at the time both of the colonies were founded. British English subsequently switched to using the French words ("courgette", "mange-tout", "aubergine") at some point after 1850. note Changes to British English over time also explain why both Australians and Americans treat collective nouns as singular, eg. "the government IS taking action" vs the English "the government ARE taking action", and why each country uses words such as "reckon" and "gotten" which went on to fall out of usage in Britain.
Australians have a tendency to retain the 'yod' (the equivalent of the 'y' sound in the word 'yoghurt'). Put simply, most Australians continue to pronounce the words 'news' as n-YOOZ, 'tune' as 'tee-OON' or 'CHEW-n' (instead of 'tune' as TOON), but drop the yod in words such as enthusiasm (enth-YOO-siasm compared with enth-OO-siasm). On that note, emu = eem-yu, not em-mu or ee-moo.
As for how we refer to ourselves:
Aussie = "Ozzy" like Ozzy Osbourne. Not "Aw-see". This is a mild colloquialism, and is more commonly associated with Bogans.
Often "I'm an Australian" becomes "I'm an Ostrayan." Worst comes to worst, it can be hard to tell whether someone's saying "I'm Astrayan" or "I'm a Strayan".
Other General Notes
There is a distinct urban vernacular evident, particularly among the working class, in places such as Sydney. People will describe awesome or cool things as 'fully sick' or 'hectic', ay? People like to end sentences with 'ay' a lot, ay? Tends to be spoken more sharply and quickly than Broad, Cultivated, or General Australian accents. Remind you of another country, eh?
Rather than being from anywhere in particular, a lot of the urban slang is quite eclectic, keeping some working-class British roots, and including various other influences, such as what the less politically correct will refer to as 'Lebo slang' (i.e. Lebanese-Australian slang). Kiwis (New Zealanders) also notably contribute to the vernacular of young people in urban areas, particularly "bro". Fully sick, bro. While sadly absent in much Australian fiction, this accent is ubiquitous in all its lyrical glory in the works of Paul Fenech, i.e. Pizza and Housos
For some speakers, the pitch goes up on the end of every sentence? Often combined with turning every sentence into a question?
This phenomenon is actually known as 'rising intonation'?
Rather, a 'rising inflection.' ...???
Some Australians use 'yeh' or 'yer' instead of 'your'. Especially when speaking fast. And, in the General or Broad accents, there can be a decided tendency to say 'yous' as the plural form of 'you'. Which in turn may evolve into 'yez' or 'yiz'.
"Footy" can mean any number of sports, depending on where you are: typically, it's rugby league in New South Wales and Queensland, and Australian Rules Football everywhere else. This cultural divide breaks along what is called 'the Barassi Line.' Soccer is sometimes called football, but never footy.
Rugby league is also commonly called just league.
Soccer is often called football among ethnic groups with whom The Beautiful Game has generally been more popular — Greeks, Italians, etc. — it's much more rare among Anglos. SBS, who, are largely responsible for popularising football/soccer in Australia, always call it football.
Australians often use litotes: e.g. they rather than say what is true they will tell you what isn't, and let you figure out what they mean, for example:
'How are you?'/'Not bad'
'When will you be back?'/'Not late'
'That was terrible'/'You're not wrong'
'How's that?'/'Really not bad' note Saying something's "not bad" does not generally have any kind of negative connotation; it really does mean 'good', rather than 'just about passable', and so is (usually) an acceptable way of describing someone's cooking, for example.
Again, we are incredibly lazy in the way we speak. Repeat after me:
Canberra is pronounced Can-Bra, not Can-be-ra. The really lazy ones will just sort of spit out a "Cambra" and then look horrified at the person enunciating each syllable.
And places like Tuggeranong = Tuggra-nong, not Tugger-a-nong. Often nicknamed as 'Tuggers', though.
Melbourne is pronounced Mel-bun, not Mel-BORN. And Brisbane is "Bris-bun" not "Bris-BAYN".
However, in Queensland, you get "Mel-BIN" and "Bris-BIN". Both are derived from the Southern Queensland unique pronunciation, which according to some Mexicans (aka people South of the Queensland/New South Wales border) makes us sound inbred. In effect, Queensland is in Australia what Alabama is in the USA.note The stereotypes are pretty much the same, except Queensland's California-style climate gives it a similarly laid-back, attractive status to some, explaining its massive New Zealand immigration and consequently, its vaguely Kiwi-sounding accent.
Now come on! Everyone knows Tasmania is the Alabama of Australia — genes don't mix across the Bass Strait.
The reason why Melbourne is pronounced "Mel-bun" is because Australian accents are non-rhotic, so the R is skipped over unless there is a vowel after it. (Think the American New England/Boston accent.note Perhaps not coincidentally, poorly-attempted New England accents are often said to sound more like Australian than anything actually spoken in New England — and sometimes, even more Australian than bad attempts at Australian accents. Coincidentally, Australia also has a region called "New England" in northeastern New South Wales, known primarily as mining country.) If a foreigner with a rhotic accent (e.g. Midwestern American) were to say Melbourne, then "Mel-burn" would be acceptable from them. But "Mel-born" is still wrong. In fact, a person from Melbourne is a "Melburnian".
Speaking of non-rhoticism, the Australian accent also features an "intervocalic intrusive 'r'": not only do Aussie leave out 'r's that have no vowel after them, but we insert 'r's between sequential vowels that are in separate syllables (or words). When an Aussie says "India are" there is a 'r' sound before the second 'a' but not after it.
The "F" word is less taboo with some communities. In fact for some people it is a universal utility word, Noun, Verb, Adjective, Direction, Comma and Exclamation. It varies just like it does in every other English-speaking country, in other words.
The "C" word is the new "F" word in some areas. Calling some guy a C means he's just not really an agreeable person. Although that's fairly lower class.
In some circles we've made the C word a term of endearment itself, or at least relatively benign — hence TISM's song "I May Be A Cunt, But At Least I'm Not A Fucking Cunt."
See also: Bugger. It's much milder than the "F" word but can have the same grammatical function. It's also a full stop and a sentence in and of itself (usually when discussing something bad that's happened, the long the conversation goes, the more likely the word "bugger" will be used by someone, often as a condolence). After its appearance in a TV ad for cars, it was ruled to be inoffensive. Bugger!
"Bloody" is used for emphasis, sometimes even right in the middle of the word it's emphabloodysizing. note Cockneys use it just as much, along with a number of other colloquialisms we have inherited.
"Bastard" has almost no negative connotation in Australia, although Australians are aware of it as an insult and still use it that way - it's just that they use it that way less often than they use it as a third-person pronoun. Memorably demonstrated in the Bodyline miniseries:
Englishman: (knocks on door, Australian opens it) I demand an apology; one of your teammates called me a bastard.
Australian: (turns to face the room) Right! Which one of you bastards called this bastard a bastard?
If someone ends every sentence with "aye" or "aa" (the long 'a' sound), then it's a fair bet they've spent time on the inland side of the Great Dividing Range in Queensland. It also has class connotations east of the Range: not something North Shore matrons tack on to their sentences. Seems like it might be common around the blue mountains.
Another Brisbane thing is to phrase everything as a rhetorical question ending in "hey". "It's pretty hot out here hey?" Or so I've heard...
It is also common, in Queensland at least, to begin a question with "hey". As in, "Hey, watcha doin' this arvo?" ("Hey, what are you doing this afternoon?"). This will be used even when you're in mid-conversation with the person you're asking, and have no need to attract their attention. It's also largely replaced "g'day" as the standard greeting.
It's becoming more popular in Victoria, except people use "Yeah?" instead of "Hey?" So, for example, someone might say "It's pretty hot out here, yeah?"
Saying "Yeah" or "Yes" to start a conversation with someone, like American/Canadian customer service people do is still usually considered rude however.
Another quirk most common in far North-East NSW/South-East QLD is to shove the conjunction "but" (and sometimes "though") from the start to the end of a phrase. Eg "I don't know but?"
Expect South Australians the strech their a's. As Danny Bhoy once described it, the way we pronounce them is like we're falling off a cliff.
Victorians, on the other hand, frequently use a short 'a' where the rest of Australia uses a long 'a' - the classic example is pronouncing the word 'castle' more like CASS-el than CAH-sel, or 'graph' with a short 'a' rather than as 'grARF'.
It's definitely CASS-el in Victoria, hence Castlemaine becomes casselmain.
Cause officially unknown, but generally thought to be because South Australia was the only part of the continent NOT originally settled as a penal colony (provided that you don't count the Northern Territory); a South Aussie accent will often sound a bit British to others. Plahnt not plant, dahnce not dance. Also, 'heaps', as in 'the sky's heaps blue today' or simply 'heaps' good will identify a Southern Aussie.
You can tell a South Aussie because they call a power pole a Stobie pole, still correct, as Stobie is the last name of the guy who invented the version used throughout SA.
Victorians (or specifically those from Melbourne) have a tendency to hate correctly pronouncing the letter "a." A collection of songs by an artist is referred to as an "Elbum" which you might purchase from a shopping mall, only you'd pronounce it like the word "mallet" without the last two letters. Oddly, though, many Melburnians pronounce their city's name with a lazy 'e' so it sounds more like "Malbourne.'
Many of the Eastern states will pronounce double oo's with a long oooo sound as opposed to the correct (to people from other states) shorter u-like sound. This makes words like pool and room funny to each the other.