BlackBerry's equivalent to the iPad has a smaller screen and is lighter than Apple's device. That's meant to make it appealing to business people on the move, the kind of people who already buy BlackBerry phones.

Nearly six million iPads were sold in the first six months, so it's easy to see why Research in Motion, the Canadian firm behind the BlackBerry, wants a bite of Apple's market. One key selling point for RIM's product is, unlike the iPad, it runs Flash video, the most popular software for showing moving images online.

Apple devices don't run Flash, thanks to a well-publicised feud between the company and Adobe, the firm behind the video technology.

Analysts say the BlackBerry tablet device is better placed than many rivals to mount an effective challenge to Apple. But it's seen as more likely to find a niche in the market than to be an outright iPad-killer.

Mark Gregory, BBC News, London

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Vocabulary

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equivalent

something with the same value, significance or qualities

appealing

attractive or interesting

on the move

travelling from one place to another

selling point

attractive quality of a product that will make people want to buy it

software

programs that tell a computer what to do

feud

long-running, angry argument

tablet device

portable computer, often without a keyboard, where you enter information directly by touching the screen

rivals

competitors

a niche in the market

a small but profitable area of commercial activity, focusing on particular types of buyers

outright

complete or obvious