other
while, during
B1
'während' means 'while' (conjunction) and 'during' (preposition). As a conjunction it introduces a subordinate clause and sends the finite verb to the clause end. As a preposition it normally governs the genitive (e.g. während des Essens); colloquial usage sometimes uses the dative.
Examples
Während der Regen stärker wurde, suchten die Wanderer Schutz unter den Bäumen, weil der Weg sehr rutschig war.
While the rain grew stronger, the hikers sought shelter under the trees because the path was very slippery.
Während des Sommers sind die Straßen voll.
During the summer, the streets are crowded.
Während ich koche, hört er Musik.
While I'm cooking, he's listening to music.
Details
Mnemonics
Imagine two overlapping clocks to show two things happening at the same time
sounds a bit like English 'where and' (two simultaneous things)
Notes
Functionally a subordinating conjunction ('while') and can also act like a preposition governing the genitive ('während des Sommers' = during the summer). Regional usage often allows dative in spoken German (während dem Sommer), but standard written German uses genitive.