This document introduces Infinispan, an open source distributed in-memory data grid. It provides high availability and elasticity through data replication across nodes. The API allows developers to treat Infinispan as a distributed concurrent hash map. Key features include transactions, persistence, querying, and map/reduce capabilities. Infinispan can be used as a local cache, cluster of caches, or autonomous data store accessed via protocols like REST and Memcached. Future plans include improvements to transactions, non-blocking state transfers, and support for cross-datacenter replication and eventual consistency.