system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it when you watch a DVD or stream a movie on your tv, it isn't completely full screen?

If I watch a movie on Netflix the movies take up my entire TV. But if I watch a DVD or stream a movie there are black bars on the top and bottom of my tv. Why?
gpt
Because that movie was formatted for a resolution different from your TV.

For example, if it was more widescreen than your TV then it would either have the sides cut off (which means you miss seeing anything happening at the sides of the screen) or they fit the width to your TV width and thus leave bars along the top and bottom.