From Mac Guides
Xcode (formerly Project Builder), is an integrated development environment (IDE) developed by Apple Computer and bundled with Mac OS X as of Mac OS X 10.3, Panther (Project Builder was bundled with previous versions).
Xcode supports development in a number of languages, including:
Major versions of Xcode are as follows:
The initial release of Xcode, first introduced on 24 October 2003, along with Panther.
Xcode 1.5 was released in August 2004, and featured dead code stripping, speed improvements to GCC, code completion for Java and AppleScript, and enhanced debugger and more. This version had several bugs that were fixed in a minor update released in November 2004.
Xcode 2.0 was released on 29 April 2005 along with Mac OS X 10.4 (Tiger). It included a new version of GCC, visual modelling and design features, integrated documentation and more.
Xcode 2.2 (released November 2005) had several bug fixes and added more support for universal binaries.
Xcode 2.3 was released on May 23 2006 and featured stability and performance enhancements.
Xcode 2.4 was released on August 7 2006, coinciding with WWDC 2006. It includes stability improvements and adds support for 64-bit Intel based Macs.
Xcode 3.0 was announced on August 7 2006 and is bundled with Leopard.
Xcode 3.1 was released on July 11, 2008.
Xcode 3.2 was released along with Snow Leopard.
Xcode 4.0 was announced on June 8, 2010, at WWDC 2010, and was released on March 9, 2011. Xcode 4 marks the biggest changes to the user interface since the Project Builder to Xcode transition. The main UI is all in one window now, and Interface Builder's functionality has been integrated into this one window. Tabs and panes are used to separate the various components. Xcode 4.0 also marks the development environment's debut on the App Store.
Xcode 4.1 was released along with Lion.
Xcode 4.2 added the iOS 6 SDK.
Xcode 4.3 added the iOS 6.1 SDK.
Xcode 5.0 was announced on June 10, 2013, at WWDC 2013, and has not been released yet.