What is a feature of adware?

Adware is a type of software that automatically displays or downloads advertisements when a user is online. One of its notable features is that it is often bundled with free software. This means that when users download and install a free application, they may inadvertently install adware as well, typically without their explicit consent or knowledge. This bundling tactic allows the creators of adware to gain exposure and generate revenue through advertisement display while providing the core software for free.

The option about requiring explicit permission before installation is not true for adware, as it frequently installs without clear consent during the installation of other software. Preventing pop-up advertisements is the opposite of what adware does; it is designed to exhibit ads. Lastly, adware does not typically engage in data encryption for security; that function is more characteristic of ransomware, which is fundamentally different from adware. This context clarifies why the correct option highlights the common association of adware with free software packages.