Customer Engagement Platforms (CEPs) are enterprise B2C and lifecycle-marketing platforms that orchestrate email, SMS, push notifications, in-app messages, web personalization, and journey delivery through a unified profile store, segmentation engine, and journey orchestrator. The category is the vendor-self-described successor to Gartner's 'Multichannel Marketing Hub' (MMH) — every leader now positions as a 'customer engagement platform.' Core capabilities include unified customer profiles with real-time event ingestion, audience segmentation with computed traits, journey orchestration across email/SMS/push/in-app/web, AI-driven send-time optimization, and cross-channel attributed revenue analytics. The market is led by Braze and Iterable (B2C lifecycle leaders), Salesforce Marketing Cloud, Adobe Journey Optimizer, MoEngage, CleverTap, Customer.io, and Klaviyo.