The current work reviews literature on the nature of stalking. Despite its nebulous nature and differing legal and clinical definitions of stalking, researchers and practitioners are referring to the same phenomenon. Stalking is chronic, consisting of a number of nuisance behaviors that appear consistent over countries and samples. Different categorizations of stalkers and their victims exist, but ex-partner stalkers are a distinctive category with respect to their prevalence, violence risk, and attrition rate. Different samples and definitions and false victimization reports obscure reliable lifetime prevalence estimates, but these appear to be around 12%-16% among women and 4%-7% among men. Stalking has deleterious effects on victims but some of the effects may be the result of stalking's exacerbating of existing vulnerabilities. Future research should focus on subgroups of stalkers and their victims, on cross-cultural investigations, and on the co-occurrence of stalking with other crimes.