die Existenz
existence
The being or presence of something or someone.
Die Existenz von Wasser auf anderen Planeten ist noch nicht bewiesen.
The existence of water on other planets has not yet been proven.

existence
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existence
The being or presence of something or someone.
Die Existenz von Wasser auf anderen Planeten ist noch nicht bewiesen.
The existence of water on other planets has not yet been proven.

'Die Existenz' (existence) is the noun related to the verb 'existieren' (to exist). The ending '-enz' often forms abstract nouns from verbs.
Viele Menschen glauben, dass Geister nicht existieren.
Many people believe that ghosts do not exist.
The economic meaning can often be recognized from verbs like 'sich aufbauen' (to build up for oneself), 'sichern' (to secure), or 'verlieren' (to lose). It usually refers to a person's professional or financial situation.
Als Selbstständiger muss man sich seine eigene Existenz aufbauen.
As a self-employed person, you have to build up your own livelihood.
In the philosophical or scientific meaning, 'Existenz' (existence) is almost always used with the preposition 'von' to say what exists or does not exist.
Die Forscher diskutieren über die Existenz von intelligentem Leben im All.
The researchers are discussing the existence of intelligent life in space.
When referring to one's basis for living, you often hear the phrases 'um seine Existenz bangen' (to fear for one's livelihood), 'seine Existenz sichern' (to secure one's livelihood), or 'sich eine neue Existenz aufbauen' (to build a new life/livelihood for oneself).
Nach dem Brand des Geschäfts bangte der Inhaber um seine Existenz.
After the fire at the shop, the owner feared for his livelihood.
stock / inventory
'der Bestand' and 'die Existenz' can both mean that something is there or continues to exist. 'Existenz' generally says that something exists. 'Bestand' emphasizes more that something remains over a longer period of time or does not disappear. Learners may confuse the words because both have to do with 'Vorhandensein' (being present / existence). If you simply want to say that something exists, 'Existenz' fits better. If it is about the continuation or preservation of something, 'Bestand' sounds more natural.

Die Existenz dieses kleinen Dorfes ist vielen Menschen gar nicht bekannt.
The existence of this small village is not even known to many people.
Der Bestand des alten Vereins ist nur durch neue Mitglieder gesichert.
The continued existence of the old club is secured only by new members.