To persist is to remain present throughout a specific period.
Persistent is a trait of any element which is predicted to remain indefinitely present in a specific context.
Persistent is a strictly specialized type of durable. A persistent element is perceived to be so durable that any probability of ending, such as functional failure, can be effectively ignored for a specific period of prediction.
Persistent is often a useful trait in strict design processes, especially for networking data instead of physical resources. This is partly because digital data can be indefinitely replicated and distributed across many network nodes, potentially including autonomous agents and intentionally redundant nodes. Distribution and redundancy can greatly reduce risks of failure. Such security can be developed in many systems, including biological reproduction, computing systems and "word of mouth" communication.