Growth terms, defined.
A glossary of the vocabulary behind marketing automation and growth, in plain language. Each entry defines one term in under a minute — deliverability, segmentation, lifecycle metrics, open-source licensing, AI agents — and points to the guide that goes deeper.
In this guide
- 01Suppression listA suppression list is a do-not-contact list — unsubscribes, hard bounces, spam complaints — checked before every send. Definition, mechanics, GDPR nuance.
- 02Double opt-inDouble opt-in is a two-step email signup: submit an address, then confirm it by clicking a link. Definition, single vs double trade-off, and GDPR nuance.
- 03Email authenticationEmail authentication (SPF, DKIM, DMARC) proves a message comes from the domain it claims. What each record does, alignment, and why it is not inbox placement.
- 04Email bounceAn email bounce is a delivery failure returned by the receiving server. Learn hard vs soft bounces, why bounce rate matters, and how to keep yours low.
- 05In-app messageAn in-app message is a banner, modal, slideout, or tooltip shown inside your product while the user is active. Definition, formats, and limits.
- 06Web push notificationA web push notification is a browser-delivered message sent via the Push API and a service worker after explicit opt-in. Definition, iOS rules, and limits.
- 07WebhookA webhook is an HTTP callback: one system POSTs event data to a URL you control the moment something happens — push, not poll. How it works and where it fits.
- 08Dynamic segmentA dynamic segment is a rule-defined audience that recomputes as events arrive — members enter and leave automatically. Definition, static vs dynamic, FAQ.
- 09Lifecycle stageA lifecycle stage is where a customer sits in their journey — lead, activated, active, at-risk, churned. Definition, typical stage models, and uses.
- 10Tracking planA tracking plan is the living spec of every event you instrument — names, properties, triggers, owners. What it contains and why drift breaks analytics.
- 11Cohort analysisCohort analysis groups users by signup date and tracks each group over time, separating real retention change from mix effects. Definition, examples, FAQ.
- 12Activation rateActivation rate is the share of new signups who reach first value within a set window. How to calculate it, pick the activation event, and improve it.
- 13Churn rateChurn rate is the share of customers or revenue lost in a period. Formula, customer vs revenue churn, and why involuntary churn is the fix founders skip.
- 14Drip campaignA drip campaign is a fixed, time-based email sequence — day 0, 3, 7 — sent in the same order to everyone. Definition, limits, and when journeys take over.
- 15Win-back campaignA win-back campaign is a message sequence for lapsed customers — re-engagement nudge, what-changed update, offer, then a final goodbye and suppression.
- 16Holdout groupA holdout group is a random audience slice excluded from a campaign to measure true incremental lift. Global vs per-campaign holdouts, sizing, and FAQ.
- 17Ideal customer profile (ICP)An ideal customer profile (ICP) describes the type of account that gets the most value from your product and retains. Definition, ICP vs persona, FAQ.
- 18AGPL licenseThe AGPL is a strong copyleft license that extends open-source obligations to network use. How section 13 works, and how AGPL compares to GPL and MIT.
- 19Multi-tenancyMulti-tenancy is an architecture where one deployment serves multiple isolated customers, called tenants, from shared infrastructure. Definition and models.
- 20Audit logAn audit log is an append-only, timestamped record of who did what, when — the evidence behind GDPR accountability and auditing AI agents' decisions.
- 21Consent recordA consent record is the stored proof that someone consented — who, when, how, the wording shown, and any withdrawal. What to store, and why GDPR requires it.
- 22Data residencyData residency is the physical location of the servers storing your data. What it means, how it differs from sovereignty, and why it is not GDPR compliance.
- 23Agent orchestrationAgent orchestration coordinates multiple AI agents on shared work: task routing, handoffs, shared context, conflict prevention, and auditable decision logs.
- 24MCP server (Model Context Protocol)An MCP server exposes a product's actions and data to AI apps such as Claude or Cursor through the Model Context Protocol. How it works, with FAQ.
Related comparisons
- Head-to-headfromHello vs BrazeCross-channel journeys at published prices, on open-source code you can self-host.
- Head-to-headfromHello vs OneSignalOneSignal leads on push; fromHello adds ad audiences and open code.
- Head-to-headfromHello vs NovuNovu delivers the notifications you code; fromHello's journeys decide who gets which message, from what they do.
- Head-to-headfromHello vs KnockKnock is closed messaging infrastructure; fromHello is open-source marketing automation.
- Head-to-headfromHello vs Customer.ioThe same event-triggered journeys, on open-source code you can self-host.
- Head-to-headfromHello vs MailchimpJourneys triggered by what people do, instead of newsletters on a calendar. Open source.
- Head-to-headfromHello vs BrevoBrevo's breadth is a CRM and WhatsApp; fromHello's is journeys on every event, LinkedIn audiences and open code.
- Head-to-headfromHello vs OrttoOrtto bundles a CDP; fromHello brings open code, LinkedIn audiences and published prices.
- Head-to-headfromHello vs IterableCross-channel journeys priced in public, on open-source code you can self-host.
- Head-to-headfromHello vs ListmonkListmonk sends newsletters; fromHello runs journeys triggered by what people do. Both AGPL.
- Head-to-headfromHello vs MauticOpen source like Mautic, with segments and journeys that react to every event, not to a cron job.
- Head-to-headfromHello vs DittofeedOpen source like Dittofeed, under active development, with in-app and ad audiences built in.
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