Needlecasting is the transmission of an individual's D.H.F. (Short for Digital Human Freight, which is the digitized form of the human mind) from the Cortical Stack to an offsite location, most often a well defended satellite or third party institution (PsychaSec in the case of Laurens Bancroft). It is this action that makes an individual impossible to kill, as they have made their own identity redundant data, which must be 'deleted' from all locations if you wish to truly kill them. It's a common practice among the Meths of the Altered Carbon world, as it provides a safeguard against real death if the stack you occupy is destroyed. This technology is one of the core reasons that the rich manage to live forever, as they distribute their vulnerability to the point where it's impossible to just kill them without a highly coordinated and expensive attack.
The use of the word 'needle' refers to the slender and concentrated beam of data that must be required to transmit such intense and important information so precisely.
Given the infrequent updates to remote storage, when a stack is destroyed it can lead to days of lost memories, depending on when the owner of the stack last needlecast.
Overview of the processEdit
Every 24-48 hours (or any predetermined time) the needlecaster will stop whatever it is they are doing and blink uncontrollably and irregularly, this is the process of needlecasting all the changes in the state of the mind from the host sleeve to the remote storage location, it doesn't take long -but if interrupted can corrupt the stack and the backup, meaning that the individual will have to revert to an even earlier 'copy', losing them multiple days of memories.
Points of interestEdit
Double-sleeving is very much illegal, and whilst it is perfectly legal to have copies of yourself stored remotely, it is only permissable to do so when you only deploy your consciousness in one sleeve at a time.