
die Quelle
source
A place where information can be found, e.g. a book, an article, or a person.
Für seine Abschlussarbeit musste er viele wissenschaftliche Quellen zitieren.
For his thesis, he had to cite many academic sources.
source
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source
A place where information can be found, e.g. a book, an article, or a person.
Für seine Abschlussarbeit musste er viele wissenschaftliche Quellen zitieren.
For his thesis, he had to cite many academic sources.

spring / source
The place where water comes out of the ground; the origin of a stream or river.
Das Wasser aus dieser Bergquelle ist besonders klar und rein.
The water from this mountain spring is especially clear and pure.

source
The origin or cause of something.
Lärm ist eine häufige Quelle für Stress am Arbeitsplatz.
Noise is a common source of stress in the workplace.

source
Something that provides energy, such as a battery, the sun, or a power plant.
Solarenergie ist eine nachhaltige und saubere Energiequelle.
Solar energy is a sustainable and clean source of energy.

source code
In computer science, the source text or source code of a computer program.
Der Programmierer hat einen Fehler in der Quelle des Programms gefunden.
The programmer found an error in the program's source code.
All meanings of 'Quelle' (source) share a common idea: it is the origin or beginning of something. That can be the beginning of a river, a piece of information, or a problem.
Wir müssen die Quelle des Problems finden.
We have to find the source of the problem.
You can easily recognize the exact meaning of 'Quelle' (source) from context. Words like 'Wasser' (water) or 'Berg' (mountain) point to the origin of a river, while 'Buch' (book) or 'Artikel' (article) refer to a source of information.
Das Wasser aus dieser Bergquelle ist sehr kalt.
The water from this mountain spring is very cold.
In academic or journalistic contexts, a source is often 'angegeben' (given/cited), 'zitiert' (quoted/cited), or 'geprüft' (checked). A good source is 'zuverlässig' (reliable) or 'seriös' (reputable).
Der Journalist nannte eine anonyme Quelle aus dem Ministerium.
The journalist named an anonymous source from the ministry.
When 'Quelle' (source) describes the cause of a feeling or state, the preposition 'für' (for) is often used. One thing is then the source of something.
Seine Kinder sind für ihn eine unerschöpfliche Quelle der Freude.
His children are an inexhaustible source of joy for him.
In computer science, 'Quelle' (source) or 'Quellcode' (source code) is used as a technical term for the readable text of a computer program. This meaning is uncommon outside the IT industry.
Der Entwickler muss den Fehler im Quelltext beheben.
The developer has to fix the error in the source code.
mother / nut
Both words can refer to the source or trigger of something. “Die Mutter” is a figurative, often personifying expression, while “die Quelle” sounds more neutral and factual. Use “Mutter” for a strong rhetorical effect and “Quelle” for a matter-of-fact statement.

Der Hass war die Quelle vieler späterer Konflikte.
Hatred was the source of many later conflicts.
Der Hass gilt als die Mutter vieler späterer Konflikte.
Hatred is considered the mother of many later conflicts.