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abstract: 'One of the main scientific objectives of the ongoing [[*Fermi*]{}]{} mission is unveiling the nature of the unidentified $\gamma$-ray sources (UGSs). Despite the large improvements of [[*Fermi*]{}]{} in the localization of $\gamma$-ray sources with respect to the past $\gamma$-ray missions, about one third of the [[*Fermi*]{}]{}-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer ([[*WISE*]{}]{}) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of $\gamma$-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the $\gamma$-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic $\gamma$-ray source. With this new IR diagnostic tool, we searched for $\gamma$-ray blazar candidates associated to the UGS sample of the second [[*Fermi*]{}]{} $\gamma$-ray catalog (2FGL). We found that our method associates at least one $\gamma$-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to $\gamma$-ray sources in the 2FGL catalog.'
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