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id: version-2.2.1-concepts-overview title: Pulsar Overview sidebar_label: Overview original_id: concepts-overview

Pulsar is a multi-tenant, high-performance solution for server-to-server messaging originally developed by Yahoo and now under the stewardship of the Apache Software Foundation.

Pulsar's key features include:

• Native support for multiple clusters in a Pulsar instance, with seamless geo-replication of messages across clusters
• Very low publish and end-to-end latency
• Seamless scalability out to over a million topics
• A simple client API with bindings for Java, Go, Python and C++
• Multiple subscription types for topics (exclusive, shared, and failover)
• Guaranteed message delivery with persistent message storage provided by Apache BookKeeper
• A serverless lightweight computing framework Pulsar Functions offers stream native data processing.
• A serverless connector framework Pulsar IO built on-top-of Pulsar Functions to make moving data in and out Apache Pulsar easier.
• Tiered Storage offloads data from hot/warn storage to cold/longterm storage (such as S3 and GCS) when the data is aging out.

Contents

• Messaging Concepts
• Architecture Overview
• Pulsar Clients
• Geo Replication
• Multi Tenancy
• Authentication and Authorization
• Topic Compaction
• Tiered Storage
• Schema Registry