system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If strings and quarks exist, why are atoms called the building blocks of matter?
gpt
Because the atom is the fundamental unit of *chemistry.* Pretty much everything interesting in the universe happens because of chemistry, and chemistry happens between atoms. The smaller constituent parts — quarks and gluons; strings are just a metaphor and don't actually exist as tangible things even if string theory is valid — do their own thing, but they don't participate in chemistry.