These are the major types of products that are competing for attention in the size range between phones and laptops. Note that none of these categories are strictly defined, and they blend into one another.

Tablet computers

Touch-screen devices with screen sizes ranging up from 5 inches (12.5 centimetres) diagonally. The iPad, with a 9.7-inch (24.5-centimeter) screen, falls in this category. Most new tablets lack keyboards, but there’s an older category of laptops with touch screens that are known as tablet PCs. Prices from $200 and up, depending on subsidies from wireless carriers. Intended for Web browsing, movie watching and reading, among other things.

Netbooks

Small, cheap laptops, with screen sizes ranging from 7 inches (17.5 centimetres) to 12 inches (30 centimeters) on the diagonal. Nearly all run Intel chips and Windows software. Prices from $100 and up, with some being subsidized by carriers. They’re mostly used for Internet browsing, social networking, e-mail and note-taking.

Smartbooks

An emerging category similar to netbooks, but with cell phone chips inside (although they generally won’t make regular phone calls.) Most run Google Inc.’s Android software, turn on instantly when flipped open, and maintain constant wireless Internet connections. Screen sizes around 10 inches (25 centimetres). Prices may be in $200 to $400 range. Can fulfil most important tasks of the netbook.

Smart phones

Phones that have sophisticated operating systems capable of running large numbers of applications. Most have touch screens around the size of the iPhone - 3.5 inches (8.8 centimetres) diagonally - but larger phones are appearing as well, inching into the territory of tablet computers. Prices from $50 and up, depending on subsidies. Web browsing and e-mail are core capabilities, but a wave of software innovation is extending smart phone functions.

E-readers

Devices like the Kindle are dedicated to reading, but they share many features of tablet computers. Many have wireless Internet connections, for instance. The two categories may merge in the future. Prices from $150 and up.