Electronically Stored Information (ESI)
Any information created, manipulated, or stored in digital form — email, documents, databases, messages, metadata — that may be subject to discovery in litigation.
Electronically stored information (ESI) is the term, drawn from the rules of civil procedure, for any information in digital form that may be relevant to litigation or an investigation — email, office documents, spreadsheets, databases, instant messages and chat, social media, voicemail, and the metadata attached to all of it.
ESI is the subject of e-discovery: when litigation is reasonably anticipated, relevant ESI must be preserved (via a litigation hold), collected, reviewed, and produced. Because ESI is voluminous, easily duplicated, and rich in metadata, it dominates modern discovery — which is why disposing of ROT on schedule (less ESI to search) and keeping records findable directly lower discovery cost and risk. Failing to preserve relevant ESI is spoliation.