NEW YORK — Apple's much-anticipated iPad is on sale.

Eager customers have been lining up outside Apple Stores and some Best Buys to be among the first to buy one as sales started at 9 a.m. today in each time zone.

Carlos Herrera came to New York from Barcelona, Spain, because it won't be on sale there for a few more weeks. The 33-year-old school teacher said he wants to show his colleagues how the device can be used in classrooms. He's turned his iPad trip into a weeklong vacation.

Still, once the initial iPad excitement settles, Apple will need to convince people who might already have smart phones, laptops, set-top boxes and home broadband connections to buy yet another device with many of the same functions.