What is auf?

"Auf" is a preposition in German language that translates to "on" or "upon" in English. It is used to indicate the location or position of an object on top of another object or surface.

For example:

• Das Buch liegt auf dem Tisch. (The book is on the table.)
• Der Hut hängt auf dem Haken. (The hat is hanging on the hook.)
• Die Katze sitzt auf dem Baum. (The cat is sitting on the tree.)

"Auf" can also be used to indicate a timeframe or deadline.

• Ich muss diese Arbeit bis auf Montag fertig haben. (I have to finish this work by Monday.)

Additionally, "auf" can be used in various idiomatic expressions such as

• auf keinen Fall (under no circumstances)
• auf gutem Weg sein (to be on the right track)
• auf eigene Faust (on one's own)

Overall, "auf" is a commonly used preposition in German language with various meanings and uses.