Was ist der Unterschied zwischen Phones, Phonemes und Allophones?

Was ist der Unterschied zwischen Phones, Phonemes und Allophones in der engl. Sprachwissenschaft?

Man findet zwar einige Beiträge hierzu im Internet, aber leider hat mich keiner weiter gebracht.
Wär super, wenn mir jemand helfen könnte!
Danke schonmal im Voraus! :)

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).