User interface, often abbreviated as UI, formerly called human interface (HI), refers to presentational and interactive design elements of potentially any tool, but usually electronic tools, specifically their hardware and/or software.
A user interface is also often referred to in context simply as an interface, or implied when used as a compound noun with some user-level concept or object, e.g.:
- post and posting interface
- edit and editing interface
- comment and commenting interface
- admin and admin interface