Help / Glossary
The words, in plain English.
Identity data has a lot of jargon. Here's what each term means for you.
- CAN-SPAM
- The US commercial email law: identify yourself, don't mislead, include a postal address and unsubscribe link, honor opt-outs.
- CCPA / CPRA
- California's privacy law, which gives residents the right to know, delete, correct, and opt out of the sale or sharing of their data.
- Company-level ID
- Identifying the organization a visitor's network belongs to. Free, and works worldwide with consent.
- Credit
- The unit you spend on any WhoLayer product. One credit buys one identified person or one found email.
- Destination
- Where identified people are sent: Slack, a webhook, Klaviyo, or HubSpot.
- DROP
- California's Delete Request and Opt-out Platform, where residents ask every registered data broker to delete their data at once.
- FCRA
- The Fair Credit Reporting Act. WhoLayer data can't be used for credit, employment, insurance, or housing decisions.
- GPC
- Global Privacy Control: a browser signal meaning "don't sell or share my data". When it's on, our tag sends nothing.
- HEM
- Hashed email: an email address turned into a fixed-length code (SHA-256) so it can be matched without sharing the address itself.
- Idempotency key
- A unique ID you send with an API request so a retry returns the saved result instead of charging again.
- MAID
- Mobile advertising ID: the resettable ID phones provide to apps for advertising.
- Match rate
- The share of visitors or records we can identify.
- Depends heavily on traffic mix. Independent industry tests of person-level ID have measured roughly 2% to 20% of traffic. We publish our own measured rates on the Trust page.
- MCP
- Model Context Protocol: the standard way AI assistants like Claude and Cursor connect to tools such as WhoLayer.
- Person-level ID
- Identifying the individual behind a visit: name, title, and contact details. US traffic only.
- Resolution
- Matching an anonymous visit or record to a known person or company.
- Reverse IP
- Looking up which organization owns the network a visit came from. It powers company-level ID.
- Risk grade
- A letter from A (safest) to D on how likely an email is to deliver. F means it won't.
- Sandbox
- Test mode that returns clearly fictional people on example.com addresses and never spends credits.
- Suppression list
- Everyone who has opted out. We check it before returning any person, and never charge for suppressed people.
- TCPA
- The US law on calls and texts. Automated calls or texts to mobiles generally need prior consent.
- Waterfall
- Trying several data sources in order until one returns a verified result, so you get better coverage than any single source.