Tip: See my guide to the 
MostThis article is an introduction to the International Phonetic Alphabet (IPA) as it is used to denote pronunciation of English words. Each symbol is treated separately, with explanation and examples that are at the same time a link to a dictionary where you can listen to the word pronounced both in American and British English.
Just one technical term used in the article: a closed syllable is a syllable which ends with a consonant (in writing; for example “writ” in “writ-ten” is a closed syllable).
[xː] long vowel
When the symbol ”ː” follows a vowel symbol, it means that the vowel is pronounced longer.
Among all English vowels, the greatest problem for most learners poses “æ”. It is somewhere between “a” in “father” and “e” in “bed”. It is usually pronounced slightly longer in American English than in British English. It is always represented by the letter “a” in a stressed closed syllable, but not all such occurrances are pronounced as [æ].
This vowel is the closest one to the sound of the letter “a” in many other languages and as such is also denoted [a] in some dictionaries. There is no reliable general rule which would tell you when “a” is pronounced as [ɑː] instead of [æ].
It is quite rare in American English to pronounce “a” as [ɑː]; it is usually pronounced [æ], as in grass, can’t, half, bath etc., all of which are pronounced with [ɑː] in British English. On the other hand, the sound is used in American English in words in which a Brit would say [ɒ] (see below), as in god, pot, top, spot—listen to both American and British pronunciation.
This vowel is quite similar to the sound of “o” many other languages. It is always represented by “o” in a closed stressed syllable, although such an “o” can also be pronounced differently (e.g. in “son”). Americans don’t use this vowel and say [ɑː] instead.
This vowel very similar to [ɑː], but it’s never pronounced long in English. It is always represented by “u” in a stressed closed syllable, or by an “o”, but both can be pronounced also in a different way.
This vowel is the closest one to the sound of the letter “e” in most other languages and is sometimes denoted by “e” in dictionaries (for example in the one I am linking to). It is usually represented by an “e” in a closed stressed syllable, but often also by “ai”, e.g. said, fair, “ae”, e.g. bear, pear, and others.
In writing, this sound is most commonly represented by “i” in a closed stressed syllable, but also unstressed “a”, “e”, or “i” is often pronounced as [ɪ]. If you find [ə] (see below) in a dictionary for a word in which you can clearly hear [ɪ] (or conversely), don’t worry; in most cases the two possibilities are interchangeable.
This is just a softer [ɪ]. It is mostly represented by “ee”, but quite often also by “ea”, single “e”, final “y” and others. It is usually long when it is in a stressed syllable and short when it is not, but not necessarily.
A similar sound to the British [ɒ], but somewhat “darker”. It is usually represented by “aw”, “al” or “au”.
The sound most similar to the sound of “u” in many other languages. It is often denoted by “u” in a closed stressed syllable (when it is not [ʌ]), but also by “oo”, “oul” and other letter groups.
[ʊ] would sound strange if it were long, so when there is a long “u” sound in English, it is pronounced somewhat “darker” than [ʊ]. It is most commonly denoted by “ew” and “oo”, but there is no way to tell when “oo” is pronounced as [uː] and when as [ʊ] (this has to be learned by heart).
Most learners of English learn very fast how to pronounce “a” when it means an indefinite article, and this is exactly the pronunciation of [ə]. It can be represented by any vowel (a, e, i, o, u) in an unstressed syllable, see the examples above. When represented by “a” or “i”, it is often freely interchangeable with [ɪ]; for example “terrible” can be pronounced either /ˈtɛrəbl/, or /ˈtɛrɪbl/.
This vowel is formed by saying [ə] and at the same time putting your tongue to the position as if you were saying the English “r” (listen to the recordings). It is denoted [ər] in some dictionaries, which is not completely precise, it is more like a long “r”). In all cases where it is used (most notably “-er” at the end of a word), a Brit would say just [ə].
Don’t confuse the symbol with [ɛ]. [ɜː] is pronounced the same as [əː] in some dialects while it is slightly “darker” in others, and many dictionaries don’t use it at all and write simply [əː]. The difference between [ɜː] and [ɝː] is the same as between [ə] and [ɚ]. The former is used chiefly in British English, the latter chiefly in American English (listen to the recordings). Dictionaries which denote [ɜː] as [əː] would denote [ɝː] as [əːr]. In writing, [ɜː] and [ɝː] are usually represented by the letter groups “ur”, “er”, or “ir”.
