How Does Subject To Financing Work?

[AJ Satcher]

I'm currently studying "subject to" financing. I understand that as the buyer, the benefit is taking over the seller's mortgage payments which may be more favorable thank taking on a PITI in the current market.

What I don't understand is, what is the benefit to the seller? The only thing I can think of is that they don't have any equity in the property or just really really don't want to deal with it anymore.

Lastly, how do the banks get involved? The Seller's bank needs to be notified of the title transfer, right? And does the buyer need their own bank to finance or are they literally just using seller's bank still when they take over the existing mortgage payments?

Looking forward to learning more about this!