SAN FRANCISCO - The much anticipated "iPad" touchscreen tablet computer made its debut in the United States Saturday:

-- about the size of a letter-sized sheet of paper, the iPad is half an inch (1.3-cm) thick and weighs 1.5 pounds (0.7 kilograms). It has a color 9.7-inch (24.6-cm) LED-display screen that allows for viewing video in high-definition

-- 16, 32 and 64 gigabytes of flash memory

-- a 16-gigabyte Wi-Fi version will be available in late April worldwide for 499 dollars. The 32GB Wi-Fi model will cost 599 dollars while the 64GB Wi-Fi model will cost 699 dollars

-- iPad models equipped with Wi-Fi and 3G will be available in late April in the United States and selected countries. The 16GB model will cost 629 dollars, the 32GB will cost 729 dollars and the 64GB model will cost 829 dollars

-- battery life of up to 10 hours from a single charge

-- runs almost all of the over 150,000 applications for the iPod Touch and iPhone available in Apple's App Store

-- an online "iBookstore" to complement the iTunes music store. iPad syncs with iTunes so applications and content downloaded from the App Store, iTunes Store and iBookstore will be automatically synched to a user's iTunes library

-- a virtual touchscreen keyboard and the ability to hook up an external physical keyboard

-- iWork, a productivity suite of applications for creating presentations or working with spreadsheets and charts

-- powered by A4, a next-generation chip which Apple said provides exceptional processor and graphics performance

-- a Software Development Kit for iPad developers to create applications

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Here are some Apple's best-known products:

o Macintosh computers: The first Macintosh computer was launched in 1984 and the line has grown to include iMac all-in-one desktop machines as well as stylishly sophisticated MacBook laptops.

o The iPod: Introduced in 2001, the hip personal music player revolutionized portable digital entertainment, culminating with its touchscreen iPod Touch MP3 player.

o The iTunes Store: Launched as the iTunes Music Store in 2003, Apple's online shop sells music, movies, and television shows for computers and its mobile devices.

o The iPhone: Apple introduced its first iPhone in 2007, combining iPod features and Internet connectivity in a touchscreen smartphone that swiftly became the mobile device of choice.

o The App Store: Apple began letting outside developers customize applications for the iPhone and iPod Touch in 2008, opening an online App Store now stocked with more than 150,000 fun, functional and hip mini-programs.