In baseball, 'heat' is slang for fastball, so 'high heat' is a high fastball.
The fastball was not invented it was just thrown and probably by the first person ever threw a baseball.
A heavy fastball is a fastball that does not have much movement but does have the appearance of rising. It is normally thrown between 85 mph and up. The opposite is a fastball that is thrown 85 mph or more with movement in and all.
Bob Gibson has the 7th fastest fastball in major league baseball history. His fastest fastball was clocked at 96 miles per hour.
4 seam fastball.
fastball, curveball, screwball, and splitter
Screwball,change up,fastball,slider,4 seam fastball,2 seam fast ball,curveball
Aroldis Chapman on the Reds
The fastball is the pitch most thrown and most hit in baseball.
Fastball, slider, curve ball, change up. Other pitches include the splitter (split finger fastball) and knuckleball.