Short answers, pulled from the story.
Goose Tatum, a former Harlem Globetrotter, is often credited with inventing the hook shot. However, Pranas Talzūnas of the Lithuanian basketball team is reported to have performed it first in an official game during Eurobasket 1937, which Lithuania won.
The skyhook is a variant of the hook shot performed at a much greater distance from the basket, producing a higher arc. It was made famous by Kareem Abdul-Jabbar, the NBA's second-place all-time leading scorer, and the name was coined by Milwaukee Bucks radio announcer Eddie Doucette during Abdul-Jabbar's time with the team.
The hook shot is thrown with a sweeping upward arc by the arm farthest from the basket, while the shooter is turned perpendicular to the basket. This angle and height make it extremely difficult for defenders to reach the ball in time. The skyhook variant was almost never blocked even at the professional level.
A traditional hook shot involves stepping and jumping off one foot, while a jump hook uses both feet for takeoff. The jump hook provides better balance and a quicker release, though the ball is not released from as high in the air. Players like Shaquille O'Neal and Dwight Howard are known for using the jump hook.
Kareem Abdul-Jabbar developed and made his skyhook famous during his NBA career, with the name coined during his tenure with the Milwaukee Bucks. The term was created by Bucks radio announcer Eddie Doucette, who described the shot as coming out of the sky.
Billy "The Hill" McGill was the number one pick in the 1962 NBA draft and was known for using the jump hook shot in both his college and professional careers. He was one of the early prominent players to use the jump hook as a signature technique.