What is the technology stack that CQ5 is built on?

The CQ5 technology stack has three main parts: Apache Sling, OSGi (Apache Felix), and Java Content Repository (JCR). Apache Sling connects with JCR using the HTTP protocol to create a RESTful framework. OSGi lets developers build modular applications with bundles that can be turned off and on while the program is running. The Java Content Repository, accessed via JSR-170 API, can access the content repository through Java, no matter how it's set up. CQ5 uses CRX, its version of JCR.