der Helm
helmet
A hard head covering that protects the head from injuries, for example during sports or dangerous work.
Beim Fahrradfahren solltest du immer einen Helm tragen.
When cycling, you should always wear a helmet.

helmet
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helmet
A hard head covering that protects the head from injuries, for example during sports or dangerous work.
Beim Fahrradfahren solltest du immer einen Helm tragen.
When cycling, you should always wear a helmet.

The word 'Helm' (helmet) is often the second part of compound nouns that refer to a specific type of helmet. Examples are 'Fahrradhelm' (bicycle helmet), 'Motorradhelm' (motorcycle helmet), 'Skihelm' (ski helmet), or 'Bauhelm' (construction helmet/hard hat).
Auf der Baustelle ist das Tragen eines Bauhelms Pflicht.
On the construction site, wearing a hard hat is mandatory.
In connection with a helmet, the verbs 'tragen' (to wear; to have the helmet on your head), 'aufsetzen' (to put on; to place the helmet on your head), and 'abnehmen' (to take off; to remove the helmet from your head) are often used.
Setz bitte deinen Helm auf, bevor wir losfahren.
Please put on your helmet before we set off.
The activity during which a helmet is worn is often expressed with 'beim' + nominalized verb. This construction is very common.
Beim Klettern trage ich immer einen Helm.
When climbing, I always wear a helmet.
hat
'der Hut' and 'der Helm' are both things you wear on your head. The most important difference is their purpose. A hat is usually clothing or fashion and may protect you from the sun or rain. A helmet is hard and is meant to protect the head from injuries, for example when cycling, riding a motorcycle, or on a construction site. Learners may confuse the words because both are head coverings. When safety is important, you say 'Helm'; for normal clothing, you are more likely to say 'Hut'.

Nele setzt vor der Fahrradtour ihren Helm auf.
Nele puts on her helmet before the bike ride.
Wegen der starken Sonne trägt Herr Hofmann heute einen Hut.
Because of the strong sun, Mr. Hofmann is wearing a hat today.