What device attaches to an electrical cord to provide additional outlets?

The device that attaches to an electrical cord to provide additional outlets is the power strip.

A power strip serves as a simple and convenient way to expand the number of available electrical outlets. It typically has multiple outlets in a single unit, allowing users to plug in several devices at once, which is especially useful in environments where wall outlets are limited. In addition to offering extra outlets, many power strips come with features like on/off switches, LED indicators, and even integrated surge protection.

While an extension cord is designed to extend reach to an existing outlet, it does not provide additional outlets itself. A surge protector, while often confused with power strips, specifically includes features to protect connected devices from voltage spikes. A junction box, on the other hand, is an electrical box used for wire connections and does not provide outlet functionality.