So how many different accents are there? Well, apparently, in total, over 100 different accents. It's actually not hard to count out 100+ actually. Take the UK for instance, they have at least four different accents. The US, at least 4. Australian mainly categorised into 3. There's minimum of 3 for Canadian. 2+ for New Zealand. Irish, Indian, Chinese, Japanese, Taiwanese, Singaporean and Mixed (like mine). Not to mention each European nation has it's own accent for speaking English.
I think you get the gist of it.
People of different backgrounds have trouble understanding people from another accent background. E.g. The Americans have a hard time understanding Australian, British accents. But, Australians have no trouble understanding either British or American accents, but they will have a hard time understanding Jamaican, Chinese, Indian styled English.
So, how do you know which accent is which?
What is the most common accent?
How can you speak different accents proficiently?
Well I can answer question 2 for you. The most common internationally is of course American accent. However, Believe it or not, the accent spoken by most right now.... is Indian. In another 5 to 10 years, Chinese accent will take over as the accent spoken the most in number of persons.
Enough chit chat, to answer question 1 and 3 is this site below:
http://www.gazzaro.it/accents/files/accents2.html
just click on the links to download or listen online for the different accents. There's also a link on the analysis of those accents as well.
Enjoy.