Field notes for the smallest things there are. Everything you have ever seen, touched, or been is assembled from the creatures on this page — a surprisingly short list.

The two great families

All matter is built from particles called fermions, and they sort into two families that never quite mix. Their fermion nature has a consequence you rely on every second: no two can share the same quantum state, which is why solid things stay solid and you don't fall through your chair.

Quarks are sociable to a fault: they carry a property called color charge, feel the strong force, and are never caught alone. Three of them clump together to make every proton and neutron.

Leptons are loners. The electron is one; so are the elusive ghostly neutrinos, which barely interact with anything at all.

Each family comes in three generations — near-identical copies at rising masses. Only the lightest generation builds ordinary matter; the heavier two are unstable and show up mainly in accelerators and cosmic rays. When the muon, a fat cousin of the electron, first turned up, the physicist I. I. Rabi reportedly grumbled, "Who ordered that?"

The carriers of force

In this picture, forces are particles too — bosons, tossed between matter particles like messages:

• Photon — carries electromagnetism; massless, infinite reach.
• Gluons — carry the strong force that binds quarks; so sticky that the quarks can never break free.
• W and Z bosons — carry the weak force behind radioactive decay; unusually heavy.

One oddball stands apart: the Higgs boson, found in 2012, a ripple in the field that hands out mass. And every particle on this page has a mirror-image antiparticle with the opposite charge.

What the guide leaves out

Here's the honest part. The Standard Model is the most precisely tested theory in the history of science — some predictions match experiment to better than a part in a billion. And it is plainly unfinished. Not in this guide:

• Gravity. It simply isn't here. Nobody has a working quantum description of it that fits alongside the rest.
• Dark matter and dark energy. Together about 95% of the universe's contents — none of it on this page.
• Why there is anything at all. The model can't say why matter outlasted antimatter after the Big Bang.

A field guide to nearly everything, in other words, that quietly admits it is missing most of the book.