  We study interactions of unparticles ${\cal {U}}$ of dimension $d_{\cal {U}}$
due to Georgi with Standard Model (SM) fields through effective operators. The
unparticles describe the low energy physics of a non-trivial scale invariant
sector. Since unparticles come from beyond the SM physics, it is plausible that
they transform as a singlet under the SM gauge group. This helps tremendously
in limiting possible interactions. We analyze interactions of scalar ${\cal
{U}}$, vector ${\cal {U}}$$^\mu$ and spinor ${\cal {U}}$$^s$ unparticles with
SM fields and derivatives up to dimension four. Using these operators, we
discuss different features of producing unparticles at $e^+ e^-$ collider and
other phenomenologies. It is possible to distinguish different unparticles
produced at $e^+e^-$ collider by looking at various distributions of production
cross sections.
