Before to build the detector we need to know the interactions (photon, charged particles, hadronic interactions, and neutrinos) and what properties we want to measure (energy, momentum, charge, life time, decay modes). How can we separably measure? Creating a detector with various combinations: a tracker, an electromagnetic calorimeter, a hadronic calometer, and a muon system.
The electrons leaves traces in the tracker and in the electromagnetic calorimeter (and stops). The fotons leaves traces in the electromagnetic calorimeter (and stops). The hadrons leaves traces in the tracker, the electromagnetic calorimeter and in the hadronic calorimeter (and stops). The muons leaves traces in all of them.
The principal function of tracking detectors is measure the tracks of emerging particles; determine charge and momentum in connection with a magnetic field; tracks are reconstructed from measured space-points.