Electronic discovery, also known as rediscovery is the electronic aspect of identifying, collecting, and generating electronically stored information (ESI) in response to requests for litigation or investigation. ESI includes, but is not limited to, emails, documents, presentations, databases, voicemails, audio and video files, social media, and websites. The processes and technologies involved in e-discovery are often complex due to the sheer volume of e-data being created and stored. Also, unlike paper evidence, electronic documents are more dynamic and often contain metadata such as timestamps, author, recipient information, and file attributes. Preservation of the original content and metadata for electronically stored information is required to rule out allegations of theft or falsification of evidence later in the course of a trial. Once both parties in the matter have identified the data, potentially sensitive documents (including electronic and printed materials) are placed in legal custody and cannot be altered, deleted, or destroyed. It collects potentially relevant data, then retrieves it, indexes it, and places it in a database. In this step, the data is analyzed to remove or isolate documents and emails that appear to be irrelevant. The data is then hosted in a secure environment and made available to reviewers who code documents according to their relationship to legal issues (contract attorneys and paralegals often participate in this document review phase).