Made from Smaller Stuff
Hadrons, the Greek for ‘heavy’ are not fundamental particles they are all made from smaller particles, quarks.
The properties of a hadron are due to the combined properties of the quarks that it is made from.
There are two categories of Hadrons: Baryons and Mesons.
Baryons Made from three quarks
The proton is the only stable hadron, all others eventually decay into a proton.
Mesons Made from a quark and an antiquark
Anti Hadrons
Anti hadrons are made from the opposite quarks as their Hadron counterparts, for example a proton is made from the quark combination uud and an antiproton is made from the combination ūūd̄
We can see that a π+ and a π– are particle and antiparticle of each other.