The impact factor (IF) of an journal is a measure reflecting the average number of citations to recent articles published in the journal. It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed to be more important than those with lower ones. However it is not a perfect metric and has its own limitations. Journals are increasingly finding new ways to improve their impact factor by increasing self citation, publishing more review articles. This correspondence discuss the fallacies of the impact factor.