Main Personality Interface

An MPI, or a Main Personality Interface, is a programmable interface that lets a user interact with a computer, navigation, etc. An MPI is usually based upon real figures or imaginative figures thus they become close to real persons. Their computation level is usually "capped" to prevent sentience; however, there are instances wherein an MPI gains self-awareness and stays within the system voluntarily.

Artificial Intelligence
While most MPIs never reach the level of Artificial Intelligence by definition, they are built to seem like it. With pre-programmed variable responses and the ability to learn, to most people, they resemble sentient beings; however that is not so.

It is possible to have an AI MPI; however, it's rare.

Closeness
Many people keep a single MPI to operate all their gadgets, computers, navigation etc. for years and years. Users and their MPIs develop close bonds where the MPI correctly understands and can predict user's reaction as well as wishes toward certain actions. They develop a symbiotic relationship wherein the MPI can swiftly and accurately execute actions as well as provide a familiar interface to foreign technology and the user can upgrade and teach the MPI much more. Due to massive data storage available to everyone, the MPI can grow almost infinitely.