How many particles?
The Standard Model

How many elementary particles are there, really?

There is no single answer. It depends on how strictly you count, and the count runs from seventeen to nine hundred ninety-five and a half.

17
17 distinct states one of every kind
02 · the four interactions

Four forces, one missing carrier

Three of the four forces have a carrier inside the Standard Model. Gravity does not; no one has found the graviton.

03 · colour confinement

Build a hadron

A lone quark has never been seen. They exist only in colour-neutral combinations: three quarks bound together, or a quark paired with an antiquark.

choose three quarks
 
Fill the slots to assemble a particle.