Question: What is 6502?
Answer: 6502 is an 8-bit microprocessor, and these resources are for 6502 assembly language programming, the instructions that tell the processor what to do.
Question: Is this how NES games are made?
Answer: Yep! Now hurry up and learn it so you can make us all new games!
Brian Parker, aka BunnyBoy (he doesn't read IM's!), has been teaching 6502 in his forum-based column called "Nerdy Nights." Following suit, MetalSlime released several articles on using sound in 6502. Check them all out if you're wanting to learn 6502: