Data enrichment
Data enrichment is adding missing fields to a list you already have — typically taking a business name and website and finding the email address, phone number, size or social profiles attached to it.
Enrichment is a lookup, not a discovery. You start from an identifier already unique enough to search on, usually a domain, and find what else is publicly attached to it. That makes it a different problem from list building, where you start from a category and a place.
The quality question is always the same: where did the field come from, and when. A provider returning an address for every row is a warning sign rather than a feature — no source has an address for every business, because many businesses never published one. A provider returning nothing for a third of rows is usually being honest.
Dates matter as much as sources. Contact data decays at roughly two to three percent a month as people change jobs and businesses close, so a field enriched eighteen months ago is materially less reliable than one enriched last week from the same source.