verb
to open, to open (a shop)
A2
aufmachen (separable) means to open (something) or to open a shop/business. Regular weak verb, separable prefix auf-, past participle aufgemacht, uses haben for perfect. Not reflexive. Use for opening doors, windows or starting a shop (ein Geschäft aufmachen). No special preposition.
Examples
Ich mache die Tür auf.
I'm opening the door.
Er machte das Fenster auf.
He opened the window.
Ich mache die Tür auf.
I'll open the door.
Details
Mnemonics
Imagine lifting a lid 'up' (auf) and the lid flies to the back — you 'open' something.
Sounds a bit like English 'off' but think 'auf' = open (opposite of closed).
Notes
aufmachen is a separable verb: in main clauses the prefix 'auf' moves to the end (ich mache die Tür auf). It is a regular (weak) verb and uses haben in perfect tenses (ich habe aufgemacht).