What was the first portable computer?

The Osborne 1 is the first commercially successful portable computer, released on April 3, 1981, by Osborne Computer Corporation. It weighed 24.5 lb, cost US$1,795, and ran the CP/M 2.2 operating system. It was powered from a wall socket, as it had no on-board battery, but it is still classed as a portable device since it could be hand-carried when the keyboard was closed. The computer shipped with a large bundle of software that was almost equivalent in value to the machine itself, a practice adopted by other CP/M computer vendors. Competitors quickly appeared, such as the Kaypro II.

Source: Wikipedia