What is "aspect ratio"?

What is "aspect ratio"?

Aspect ratio describes the ratio of the height to the width of the image that's on the screen. Traditional TV, standard definition TV had a 4:3 aspect ratio which made it fairly square. The newer types of TV's are 16:9 the HD ratio, 16:9 aspect ratio which makes it more rectanglular. Where this becomes important is when you're veiwiing content on your TV, if you're veiwing older material it will stretch to fill the screen. If you want to avoid the stretch, you'll select viewing the content in 4:3 aspect ratio and you'll see bars either on the sides or on the top and bottom of that picture.