What are common treatments for skin pigmentation?

As I get older each year, I definitely seem to have more pigmentation problems on my face.
Freckles are a given, but I'm starting to see more spots and my skin is starting to look darker.
I feel like it all boils down to skin pigmentation.
There are various creams and packs, but they definitely feel more like preventative measures.
If skin pigmentation has already occurred, it seems like there is no other way than dermatological treatment, but I am not sure if that is true.
In this case, I will have to find out through consultation, but I am curious about what kind of treatment is usually performed.