In the Interplanetary age simulated personalities were regularly created using large databases of information about the individual concerned, sometimes derived from accumulated evidence such as audiovisual recordings or other historical evidence, or from their own diaries or lifelog. Artificial personalities of this sort were known as simulacra, or Simms.
When Direct Neural Interfacing began to allow the creation of extensive external mental processors (known as exoselves), some individuals attempted to use this technology to create full copies of the original by uploading as much information as possible to the exoself personality via their DNI linkage. Since the data stored by the exoself could be easily copied, this data could be used to construct a remarkably accurate description of the individual's personality.
These attempts at detailed copying became known as Evocations and were considerably more accurate than the early simm copies of a few decades before. However detailed analysis of the evocation's memories and personality would eventually reveal significant differences, so evocation was not widely accepted as a true method of uploading a person from a biological to an electronic state.
In the modern era evocations of deceased or distant persons are sometimes produced when a true upload is not available or possible. By extracting data from the exoself database a reasonable copy of the original person can be created; sometimes after an accident or other incident the exoself is all that remains of an individual, and an evocation created from that exoself may be produced for various purposes.