how do ac-dc phone chargers work?

i mean i don't get it did they use transformers because i won't see them fitting a trnsformer in to something so small is there a difrent way they make it can you explain maybe even show me an example in a scymatic
ftr(for the record) this is not for a school project or something i just wanted to know...

They're usually switch mode power supplies so the transformers are smaller.

switch mode?

The transformer is small because they use a high frequency oscillator instead of the low frequency 50Hz or 60Hz from the mains.

The charging circuit is inside the phone. You are talking about just a power supply.