der Hintergrund
background
The part of an image, stage, or scene that is farthest away from the viewer.
Im Hintergrund des Familienfotos kann man das Meer sehen.
In the background of the family photo, you can see the sea.

background
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background
The part of an image, stage, or scene that is farthest away from the viewer.
Im Hintergrund des Familienfotos kann man das Meer sehen.
In the background of the family photo, you can see the sea.

The word is made up of 'hinter' (behind) and 'Grund' (ground, reason). This origin explains the different meanings: the visual background (what lies behind the main subject) and the causal background (the reasons behind an event).
Der wahre Hintergrund des Streits wurde erst später bekannt.
The true background of the dispute only became known later.
The preposition 'in' ('im Hintergrund' — in the background) usually describes a position or state. The preposition 'vor' ('vor dem Hintergrund' — against the background) is often used to give a context or reason for an event.
Im Hintergrund der Bühne stand ein Chor.
A choir stood in the background of the stage.
When it is about causes and connections, 'Hintergrund' (background) is often combined with adjectives such as 'politisch' (political), 'historisch' (historical), or 'wirtschaftlich' (economic). Typical verbs are 'aufklären' (to clarify), 'verstehen' (to understand), or 'recherchieren' (to research).
Ein Journalist deckte die wirtschaftlichen Hintergründe des Skandals auf.
A journalist uncovered the economic background of the scandal.
To describe a person's origin or experience, 'Hintergrund' (background) is often connected with 'akademisch' (academic), 'beruflich' (professional), or 'familiär' (family-related). A very common phrase is 'einen Migrationshintergrund haben' (to have a migration background).
Bewerber mit einem technischen Hintergrund werden bevorzugt.
Applicants with a technical background are preferred.
The expression 'sich im Hintergrund halten' (to stay in the background) is reflexive. This means the verb 'halten' (to hold/stay) is always used with a reflexive pronoun (mich, dich, sich, etc.) that matches the person.
Bei Familienfesten halte ich mich lieber im Hintergrund.
At family celebrations, I prefer to stay in the background.
In computer language, 'im Hintergrund' (in the background) describes processes that are not directly visible to the user. Typical verbs in this context are 'laufen' (to run) or 'ausführen' (to execute).
Während du arbeitest, laufen mehrere Updates im Hintergrund.
While you work, several updates are running in the background.
connection / context
'der Zusammenhang' and 'der Hintergrund' can both help you understand an event or a statement better. 'Zusammenhang' refers more to the connection between things or the context in which something appears. 'Hintergrund' refers more to the causes or circumstances behind an event that are not immediately visible. They can be confused because both ask for additional explanation. In practice: if you are asking how things are connected, 'Zusammenhang' fits. If you are asking why something happened or what is behind it, 'Hintergrund' fits.

Der Bericht nennt den politischen Hintergrund der Entscheidung.
The report names the political background of the decision.
Frau Richter erklärt den Zusammenhang zwischen den hohen Mieten und den neuen Regeln in der Stadt.
Ms. Richter explains the connection between the high rents and the new rules in the city.