The frequent appearance of popup ads while browsing the web is an indication of what type of malware?

The frequent appearance of popup ads while browsing the web is primarily indicative of adware. Adware is a type of software that automatically displays or downloads advertising material (often unwanted) when a user is online. Its primary function is to generate revenue for its developer by displaying ads, which can be intrusive and interfere with a user's browsing experience.

Unlike other types of malware, such as spyware, which is more focused on gathering user data without consent, or ransomware, which aims to encrypt a user's files and demand payment for their release, adware specifically targets advertising. A Trojan horse, on the other hand, refers to a type of malware that disguises itself as a legitimate program but performs harmful activities once activated, but it does not specifically relate to advertising popups.

In summary, the nature of adware is directly linked to the unwanted and frequent advertisements experienced during web browsing, making it the correct identification for the type of malware that causes those popup ads.