  Phenomenology of the notion of an unparticle U, recently perceived by Georgi,
to describe a scale invariant sector with a non-trivial infrared fixed point at
a higher energy scale is explored in details. Behaving like a collection of d_U
(the scale dimension of the unparticle operator O_U) invisible massless
particles, this unparticle can be unveiled by measurements of various energy
distributions for the processes Z to fermion pair + U and e-e+ to gamma U at
e-e+ colliders, as well as mono-jet production at hadron colliders. We also
study the propagator effects of the unparticle through the Drell-Yan tree level
process and the one-loop muon anomaly.
