Defining forgetting broadly as any failure to express an association after it was acquired, there appear to be four families of contributing mechanisms: (1) decay, (2) inadequate retrieval cues present at test, (3) displacement from working memory during acquisition or test, and (4) associative interference. Examination of the first three mechanisms suggests that the fourth is often the real underlying mechanism in those cases. The broad varieties of associative interference will be reviewed, with a critical question being whether they all obey the same basic rules. Orthogonal to the mechanism(s) of forgetting, one might ask about the fate of forgotten memories. I will present evidence that in many cases forgetting is reversible and recovery from forgetting fundamentally surprisingly challenges prevailing accounts of such diverse instances of forgetting as so-called disrupted reconsolidation and infantile amnesia. An argument will be presented that forgetting is active, inhibitory, and usually highly beneficial.