Are there multiple endings to Dark Souls? If yes, how many, and how is it determined which ending will be played? Please try to not tell what the ending are, I'm still at the beginning of the game, and I don't want to be spoiled too much.
There are two, and they are determined by a choice you have to make following the final boss fight.
You don't need to become a Darkwraith or form a "pact" with Frampt (you dont even need him to place the lordvessel, you can just jump down the hole and warp out),
The ending is only based upon walking away or lighting the bonfire. As to which ending is better: walking away is basically destroying the gods powers and the humans takeover. Lighting the bonfire kills your character until NG+, NG++, etc.
The walk away ending is better for the humans as they become well, kind of like gods, but lighting the bonfire keeps the gods alive and ruling.
Basically to activate the Good (chosen undead)ending you need to saciate the lord vessel with Frampt the worm that awakens when you ring both bells. the second Evil ending is a lot more difficult in my oppinion you have to become a darkwraith by defeating the four kings while still being in possesion of the lordvessel. once the four kings are defeated another worm/ serpent whos name escapes me appears speak with him and saciate the lord vessel afterwards the rest of the game carries on as normal.
in regards to the comments, it penumltimately boils down to lighting the bonfire after the final boss fight. but to discover that you can either leave it or light it you would probably need to find the questlines as stated above because as a new player you would probably not have realised.