The journal impact factor is a measure of the frequency with which the "average article" in a journal has been cited in a particular year. The impact factor will help you evaluate a journal's relative importance, especially when you compare it to others in the same field. The impact factor is calculated by dividing the number of current citations to articles published in the two previous years by the total number of articles published in the two previous years.
a simple ratio of citations and papers
A quantitative measure of the frequency with which the "average article" published in a given scholarly journal has been cited in a particular year or period, this is used in citation analysis
A basis for judging the quality of journals. A journal with a high impact factor (the average number of citations per article published, as determined by the Science Citation Index) is apparently used more than a journal with a low impact factor.
Factor having power to produce alteration in an environmental system.
The Impact factor, very often abbreviated IF, is a measure of the citations to science and social science journals. It is frequently used as a proxy for the importance of a journal to its field.