Currently, there is no clear-cut definition of what stalkerware is. This term is interpreted differently by various experts and journalists in the field of information security. Most often, the definition of stalkerware (also called spouseware or “legal spy”) is used to refer to software that is used for stalking — the unwanted, sometimes intrusive attention of one person aimed at another, which can also include spying one person on another. The term itself appeared due to the increased use of commercial monitoring software for spying on spouses or intimate partners, which could lead to abuse (harassment, family violence, etc.).
The problem is that due to the fact that some of the programs can be used in harmful ways, this label is often placed not only on deliberately malicious software (i.e. software designed to gain UNAUTHORIZED access), but also on quite legal monitoring products that the user is fully authorized to install on his own devices for various purposes (parental control, employee monitoring, etc.).
There is also an opinion that stalkerware includes any systems that stealthily collection data on users, including trackers from advertising and social media. However, since such a collection of information is not related to stalking, this definition is not correct.