Does it cost money to publish a game?

I'm curious to know, does it actually cost money to publish a game? I understand that there are various expenses involved in the development process, but what about once the game is ready for release? Are there any upfront costs or fees associated with getting a game out into the market? I'm particularly interested in the financial side of things, so if you could provide a detailed breakdown of the potential costs involved, that would be greatly appreciated.