Jetpack adds many popular features from WordPress.com to self-hosted WordPress sites by connecting them to the WordPress.com infrastructure, providing features like a free global CDN (Photon), analytics (Stats), related posts powered by Elasticsearch, social sharing (Publicize), and brute force protection. It also allows extending and customizing Jetpack through staging sites for testing without sending data to WordPress.com and development sites. Popular Jetpack features discussed in more detail include Related Posts, Stats, VideoPress, and Carousel. Resources for developing with Jetpack and the WordPress.com API are provided.