What is the difference between phoneme, phone and allophone?

- A phoneme is the smallest contrastive linguistic unit which may bring about a change of meaning. For example 'mat' and 'bat'. Phonemes are based on spoken language and recorded by IPA (International Phonetic Alphabet). They are written beetween slashes..e.g. /p/

- Allophones are variations of phonemes. So, they are set of possible spoken sounds used to prounounce one single phoneme. e.g. [pʰ] (as in pin) and [p] (as in spin) are allophones of the phoneme /p/. They are written in brackets.

- A phone is a unit of speech sound. It may refer to any speech sound or gesture without regard of its place in phonology of a language. A phoneme is a set of phones or a set of sound features that are thought of as the same element within the phonology of a particular language.

the ^phoneme is the sound speech which makes the word mean diffrently for exemple: pit and bit 

the allophone : means the one way of prounouncing a phoneme as one of the slightly different ways that a phoneme can be pronounced. For example, the /p/ in the word ‘pill’ is slightly different from the /p/ in the word ‘spill’

In general: allophones = conditioned variants of a phoneme; generated by phonological conditioning(= a matter of language-specific ‘rules of pronunciation’)

Contrastive systems range in complexity from languages with less than20 distinctive consonants and vowels to languages with60 or more. English, depending on the particular dialect, has up to24 consonants and up to about20 vowel sounds (Warlpiri (=Australian Aboriginee language): only3 distinctive vowel sounds — /a/, /i/, and /u/)

well a difficult topic for linguistics students anyhow, to get the proper understanding we should start with the phone

phone simply mean letters in English like  < m> and <n> these letters are concrete property and they have no meaning . NOTE Words are made with letters 

phoneme basically IS abstract reality in our mind with complete meaning. Phoneme is made of one or two phones.  for example word /map/  contain three letters or phones by changing any of  three phoneme meaning  changes. /tap/   /nap/    /cap/   same as /mat/   so on . Note word /day/ has three phones but two phoneme when we transcribe /dei/ .

Allophone has variation in sound without any effect /  only change in sound not in meaning , for example /t/ sound is phoneme having complete meaning like   / tap/ but when /t/ is dropped or flap or stop there is no difference in meaning like /matter / t / is flap as madder . matter or madder no difference,

Phoneme: The smallest phonetic unit in a language that is capable of conveying a distinction in meaning, as the m of mat and the b of bat in English.

Allophone: A predictable phonetic variant of a phoneme. For example, the aspirated t of top, the unaspirated t of stop, and the tt (pronounced as a flap) of batter are allophones of the English phoneme /t/ 

Phones: are speech sounds