Can you tell me any website which has best pronunciation of the words. I, frequently, find many words,of which I want to know the pronunciation.But, I can't know because of non-availability of any source. thanks.
Cambridge Dictionaries Online http://dictionary.cambridge.org/, is a good resource. It has sound recordings with American and English pronunciations of words.
I'd like to recommend Macmillan's dictionaries to learners. They list pronunciations for both British and American English, and they have not only IPA transcriptions, but also recordings you can listen to.
For example, try looking up the word car. You can find entries on Macmillan's site for both British pronunciation and American pronunciation. In each entry, you can read a transcription of the word in IPA, and you can also click the "Pronunciation" button to hear a recording.
Try reading along with the transcriptions while you listen to the recordings. You'll be able to hear what the symbols mean in context. Of course, you can also consult Macmillan's guide to pronunciation symbols, including Adrian Underhill's phonemic chart.
I've found this web site helpful if you're looking for information on how people actually pronounce words in different parts of the world:
Not all these pronunciations are the "correct" pronunciations, but they are by native English speakers, and they highlight regional differences in pronunciation.