  The IceCube Neutrino Observatory is an array of 5,160 photomultipliers (PMTs)
deployed on 86 strings at 1.5-2.5 km depth within the ice at the South Pole.
The main goal of the IceCube experiment is the detection of an astrophysical
neutrino signal. In this contribution we present the results of the point
source analysis on the data taken from April 2008 to May 2011, when three
detector configurations were operated: the 40-string configuration (IC-40), the
59-string configuration (IC-59) and the 79-string configuration (IC-79). No
significant excess indicative of point sources of neutrinos has been found, and
we present upper limits for an $E^{-2}$ muon neutrino flux for a list of
candidate sources. For the first time these limits start to reach $10^{-12}$
TeV$^{-1}$ cm$^{-2}$ s$^{-1}$ in some parts of the sky.
