Other forms: chyrons
A chyron is a banner with text that is displayed at the bottom of a television screen. Think of boxes with subtitles, or a box showing the name of a person being interviewed.
Originally, Chyron was the name of a company that made graphics for television shows. The company came up with the most popular system for displaying things like closed captions and titles onscreen. They became so popular, in fact, that the types of graphics they specialized in started being called by their name, even in cases where some other company had added them. They're sometimes also called lower third text because they appear somewhere on the bottom third of the screen.