  Equipping an experiment at FCC-ee with particle identification (PID)
capabilities, in particular the ability to distinguish between hadron species,
would bring great benefits to the physics programme. Good PID is essential for
precise studies in quark flavour physics, and is also a great asset for many
measurements in tau, top and Higgs physics. The requirements placed by flavour
physics and these other applications are surveyed, with an emphasis on the
momentum range over which PID is necessary. Possible solutions are discussed,
including classical RICH counters, time-of-flight systems, and d$E$/d$x$ and
cluster counting. Attention is paid to the impact on the global detector design
that including PID capabilities would imply.
