High impact journals are journals ranked by organizations such as Eigenfactor.org and Journal Citation Reports. Eigenfactor is free and ranks journals much like Google ranks websites using 5-year citation data. Journal Citation Reports defines the journal impact factor as the average number of times articles from the journal published in the past two years have been cited in the JCR year.

Journal Citation Reports , published by Web of Science goes on to say, "The impact factor mitigates the importance of absolute citation frequencies. It tends to discount the advantage of large journals over small journals because large journals produce a larger body of citable literature. For the same reason, it tends to discount the advantage of frequently issued journals over less frequently issued ones and of older journals over newer ones. Because the journal impact factor offsets the advantages of size and age, it is a valuable tool for journal evaluation."