GlassFish is an application server with all the features you would expect from a full-featured Java EE 6 products.
Some of those features are delivered via a number of (sub-)projects which are listed below.

Separate projects encourage reuse and contributions as they can be used outside of GlassFish, create their own communities and of course be integrated and delivered in a polished GlassFish product.

	Description	Project home, Wiki, etc.	Downloads
Mojarra	Production-Quality JSF (JavaServer Faces) Reference Implementation (RI)	Mojarra Web Site | FAQ
Grizzly	NIO-based Web framework at the heart of GlassFish (HTTP, IIOP, WebSocket, etc).	Grizzly Web Site | Getting started
Metro	High-performance, extensible, and easy-to-use SOAP web service stack. Contains both the JAX-WS implementation as well as advanced WS-* implementations.	Metro Web Site | Overview
Jersey	Production-quality, JAX-RS Reference Implementation for building RESTful Web services.	Jersey Web Site | Wiki
Shoal	Scalable and dynamic clustering framework used as the Group Management System (GMS) in GlassFish.	Shoal Web Site
HK2	Micro-Kernel (module subsystem and component model) used since GlassFish 3.x.	HK2 Web Site
UpdateCenter	Network repository-based toolkit for GlassFish 3.x with IPS.	UpdateCenter Web Site | Wiki
OpenMQ	Complete message-oriented middleware and JMS implementation. Usable standalone or integrated in GlassFish.	OpenMQ Web Site | Introduction
EclipseLink	Production-quality JPA reference implementation and a lot more.	EclipseLink Web Site | Wiki