Xcode

Xcode is the main development tool in use for creating Applications for Mac OS X.

Editions
Apple currently produce two editions

Xcode for Mac OS X development
This edition contains all the tools required to build applications for Mac OS X.

Xcode for iPhone development
This edition contains all the tools required to build applications for iPhones.

Parts
Xcode contains many tools, the main one is Xcode itself, which is a project manager and code editor.

Open source tools
To build applications gcc (the GNU C Compiler) is used along with Carbon or Cocoa.

Additional tools
Additional tools include
 * Dashcode
 * Instruments
 * Interface Builder
 * Quartz Composer

Audio

 * AU Lab
 * HALLab

Video

 * Core image fun house
 * OpenGL driver monitor
 * OpenGL profiler
 * OpenGL shader builder
 * Pixie
 * Quartz Composer visualizer
 * Quartz debug

Performance

 * BigTop
 * CHUD
 * MallocDebug
 * ObjectAlloc
 * Sampler
 * Shark
 * Spin Control
 * Thread Viewer

Utilities

 * Accessibility Inspector
 * Accessibility Verifier
 * Applet Launcher
 * Bluetooth Explorer
 * PacketLogger
 * Clipboard Viewer
 * CrashReporterPrefs
 * FileMerge
 * Help Indexer
 * Icon Composer
 * IORegistryExplorer
 * iSync Plugin-in Maker
 * Jar Bundler
 * MacPython
 * PackageMaker
 * Property List Editor
 * SleepX
 * Repeat After Me
 * SRLanguageModeler
 * Syncrospector
 * USB Prober