runter
down
Colloquial short form of 'herunter' (down); expresses movement from a higher to a lower position.
Kommst du bitte vom Baum runter?
Could you please come down from the tree?

down
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down
Colloquial short form of 'herunter' (down); expresses movement from a higher to a lower position.
Kommst du bitte vom Baum runter?
Could you please come down from the tree?

'Runter' is the colloquial and very common short form of 'herunter' (down). In everyday language, 'runter' is almost always used, while 'herunter' sounds more formal.
Holst du mir bitte die Tasse vom Regal runter?
Could you please get the cup down from the shelf for me?
'Runter' often functions like a separable prefix in verbs that describe downward movement (e.g. 'runtergehen' (to go down), 'runterfallen' (to fall down), 'runterkommen' (to come down)). In a main clause, 'runter' then stands at the end of the sentence.
Die Katze kommt den Baum nicht mehr alleine runter.
The cat can't come down from the tree by itself anymore.
When it comes to prices, temperatures, or other values, 'runter' in combination with verbs like 'gehen' (to go) or 'sein' (to be) means a reduction or decrease.
Die Zinsen für Kredite sind wieder etwas runter.
Interest rates for loans are down a bit again.
In a digital context, often with verbs like 'laden' (to load) or 'ziehen' (to pull), 'runter' always means 'herunterladen' (to download).
Ich muss mir die neueste Version der Software runterladen.
I need to download the latest version of the software.
In the combination 'mit etwas runter sein' (to be worn out from something) or 'total runter sein' (to be totally down), the word describes a state of exhaustion or dejection. Here it is used like an adjective after the verb 'sein' (to be).
Nach dem Marathon war ich mit meinen Kräften völlig runter.
After the marathon, I was completely at the end of my strength.
high
'hoch' and 'runter' both belong to the area of up and down, but they work differently. 'hoch' describes a position, a height, or a large value: 'ein hoher Berg' (a high mountain), 'hohe Preise' (high prices). 'runter' usually describes movement downward or a decrease: 'die Treppe runter' (down the stairs), 'die Preise gehen runter' (prices are going down). Learners may confuse them because both have to do with direction or height. The important point is: 'hoch' often describes what something is like; 'runter' more often describes where something is moving to or that something is becoming less. 'runter' is also colloquial.

Nach dem Sommer gehen die Preise für viele Fahrräder wieder runter.
After the summer, prices for many bicycles go back down.
Die Miete in dieser Stadt ist sehr hoch.
The rent in this city is very high.