In computing, a user interface is the space where interaction between humans and machines occurs. A rich user interaction is an interface model of a rich client

Fat client

A fat client is a computer in client–server architecture or networks that typically provides rich functionality independent of the central server...

. It is an interaction model that can support several input methods and that responds intuitively and in a timely fashion. As a rule of thumb, to be a rich user interaction, the model must perform in practice at least as well as current desktop applications, such as word processor

Word processor

A word processor is a computer application used for the production of any sort of printable material....

s and spreadsheet

Spreadsheet

A spreadsheet is a computer application that simulates a paper accounting worksheet. It displays multiple cells usually in a two-dimensional matrix or grid consisting of rows and columns. Each cell contains alphanumeric text, numeric values or formulas...

s.