
das Handy
mobile phone / cell phone
A portable, cordless mobile telephone used for mobile communication.
Mein Akku ist leer, ich muss mein Handy aufladen.
My battery is dead; I need to charge my cell phone.
mobile phone / cell phone
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mobile phone / cell phone
A portable, cordless mobile telephone used for mobile communication.
Mein Akku ist leer, ich muss mein Handy aufladen.
My battery is dead; I need to charge my cell phone.
'Das Handy' (mobile phone/cell phone) is a typical example of 'Denglisch'. Although it sounds English, it is not the English word for a mobile phone. In English, you say 'mobile phone' or 'cell phone'. The English adjective 'handy' means 'practical' or 'useful'.
Darf ich mal dein Handy benutzen? Mein Akku ist leer.
Can I use your cell phone for a second? My battery is dead.
In everyday life, 'Handy' (mobile phone/cell phone) is combined with many typical verbs. These include: 'das Handy laden/aufladen' (to charge the phone), 'am Handy sein' (to be on the phone) or colloquially 'am Handy hängen' (to be glued to one's phone), 'aufs Handy schauen' (to look at one's phone), or 'eine Nummer im Handy speichern' (to save a number in one's phone).
Er ist ständig am Handy und hört gar nicht zu.
He's constantly on his phone and isn't listening at all.
'Handy' (mobile phone/cell phone) is a very productive word and forms the basis for many useful compounds. Examples are 'Handynummer' (cell phone number), 'Handyhülle' (phone case), 'Handyvertrag' (cell phone contract), or 'Handy-Akku' (phone battery).
Ich brauche eine neue Handyhülle, meine alte ist kaputt.
I need a new phone case; my old one is broken.
telephone
Handy specifically means a portable telephone for mobile use. Telefon is the more general term and can also refer to a Handy; especially in contrast to Handy, however, it often means a permanently installed telephone.

Unterwegs telefoniere ich mit dem Handy.
I make calls on my mobile phone when I’m out and about.
Zu Hause telefoniere ich mit dem Telefon im Flur.
At home, I make calls on the telephone in the hallway.