Quarks are thought to be the basic component of what?

There are thought to be a few elementary particles which can't be broken down any further and these are mainly Quarks, Leptons and Gauge Bosuns.

Of course it may just mean that our equipment isn't advanced enough yet to further break these particles apart but at present we are fairly confident that these are true elementary particles.

there's the Gauge Boson. This is basically the means of transmitting the energy that comes from the four forces - for example the actual method by which a magnet exerts an attractive force on a drawing pin or whatever is thought to be by an exchange of massless, virtual particles. In the case of the magnet that would be the gauge boson that relates to electromagnetism, the photon.

Quarks are thought to be the basic component of protons and newtons.