Mac OS X uses Darwin.
Mac OS X uses a Mach kernel and FreeBSD utilities at it's core.
Each version of Apple's Mac OS X is named after a big cat. Mac OS X 10.5 is called "Leopard".
The Mac OS X Tiger install DVD is the DVD that allows you to install 10.4 software onto your Mac. 10.4 is Tiger, and so it is called Mac OS X Tiger.
OS X Leopard Which stands for Operating System 10.
The second name of Mac OS X v10.4.5 is Mac OS X v10.4 Intel.Mac OS X 10.4 was known as Mac OS X Tiger.
Mac OS X is one of the major releases of operating systems from Apple Inc. It features a low level Mach_kernel, underlying Unix OS, a 3D graphical user interface. Mac OS X can only be installed on computers made by Apple Inc. Recent versions of Mac OS X include: Mac OS X 10.3 Panther, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard. Starting in Mac OS 10.5 an automatic backup utility called Time Machine is available. The current version is Mac OS X 10.10 and an early release version of Mac OS X 10.11 is available to install.
I'm not sure if you mean the foundation of Mac OS X itself, or of the desktop. The desktop is a part of Mac OS X's Finder application which is written by Apple from scratch in Objective-C using the Cocoa framework. Mac OS X itself's core is Darwin, a UNIX operating system based on the open source FreeBSD.
Mac OS X 10.4 (Tiger) needs to be purchased as it is not possible to update from Mac OS X 10.2.8
Mac OS X is an operating system released by Apple Inc. It is designed for Apple branded computers, which is why you will never see a Dell, or an HP computer run Mac OS X. There are only two important versions of Mac OS X, Mac OS X Server, and regular Mac OS X. Mac OS X server was designed for servers, while regular Mac OS X was designed for most computers. The current version of Mac OS X (10.6) is named Snow Leopard.
The search feature in Mac OS X is called Spotlight.
To upgrade from Mac OS X 10.4 (Tiger) to 10.5 (Leopard) you will need to buy a boxed version of Mac OS X 10.5. If you have a Mac with an Intel processor you can go straight to Mac OS X 10.6 (Snow Leopard) which is a cheaper upgrade option.
Yes, it is. Any type of MacBook that comes out now is a Mac OS X. The most recent version of Mac OS X is Mac OS X Lion, coming out soon.