wärmen
to warm
To deliberately expose something to a heat source in order to raise its temperature.
Ich wärme mir schnell die Suppe von gestern in der Mikrowelle.
I'll quickly warm yesterday's soup in the microwave.

to warm
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to warm
To deliberately expose something to a heat source in order to raise its temperature.
Ich wärme mir schnell die Suppe von gestern in der Mikrowelle.
I'll quickly warm yesterday's soup in the microwave.

The verb 'wärmen' (to warm) belongs to the word family of 'warm' (adjective) and 'die Wärme' (warmth; noun). All these words refer to a pleasantly high temperature.
Die Frühlingssonne wärmt schon angenehm.
The spring sun is already pleasantly warm.
'Wärmen' (to warm) can be used in three ways: transitively (you warm something), reflexively (you warm yourself), or intransitively (something keeps warm by itself).
Kannst du bitte die Milch für das Baby wärmen?
Can you please warm the milk for the baby?
When you deliberately heat something, typical objects are foods and drinks. Common combinations are 'eine Suppe wärmen' (to warm a soup), 'das Essen wärmen' (to warm the food), or 'seine Hände wärmen' (to warm one's hands).
Er wärmte seine kalten Hände an der heißen Tasse.
He warmed his cold hands on the hot cup.
When you warm yourself, the heat source is often given with the prepositions 'an' (+ dative) or 'in' (+ dative).
Die Wanderer wärmten sich am Lagerfeuer.
The hikers warmed themselves by the campfire.
In this meaning, the subject of the sentence is the source of warmth, often a piece of clothing, a blanket, or the sun. The verb describes a property of that thing.
Ein guter Schlafsack wärmt auch in kalten Nächten.
A good sleeping bag keeps you warm even on cold nights.
to cool
'kühlen' and 'wärmen' are opposites when it comes to temperature. 'kühlen' makes something or your own body colder. 'wärmen' makes something or your own body warmer, often through a heat source such as the sun, a heater, or a fire. The words can be confused because both are often used in everyday life with the body, weather, or food. The direction is what matters: when it is hot, you want to cool yourself off; when it is cold, you want to warm yourself.

Sie wärmt ihre Hände an der Tasse Tee.
She warms her hands on the cup of tea.
Nach dem langen Spaziergang in der Sonne kühlen wir uns im Schatten.
After the long walk in the sun, we cool ourselves off in the shade.