The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in "16:9". For an "x":"y" aspect ratio, no matter how big or small the image is, if the width is divided into "x" units of equal length and the height is measured using this same length unit, the height will be measured to be "y" units. 

In, for example, a group of images that all have an aspect ratio of 16:9, one image might be 16 inches wide and 9 inches high, another 16 centimeters wide and 9 centimeters high, and a third might be 8 yards wide and 4.5 yards high. 

The most common aspect ratios used today in the presentation of films in cinemas are 1.85:1 and 2.39:1. Two common videographic aspect ratios are 4:3 (1.3:1), the universal video format of the 20th century, and (1.7:1), universal for high-definition television and European digital television. Other cinema and video aspect ratios exist, but are used infrequently. 

In still camera photography, the most common aspect ratios are 4:3, 3:2, and more recently being found in consumer cameras 16:9. Other aspect ratios, such as 5:3, 5:4, and 1:1 (square format), are used in photography as well, particularly in medium format and large format.
what is a common ratio used in films?
is there one for camera photography?
what is it?
any others used?
what?
What does aspect ratio do?
how would you express this?
does x stand for height?
what does it stand for?
Does Y stand for circumfrence?
what does it stand for?
what is the aspect ratio for the universal video format?
for the 19th century?
what century?
what is the aspect ratio for high def tv?
are there different aspect ratios used in camera photography with different formats?
what seperates the two numbers?
1.85:1
The most common aspect ratios used today in the presentation of films in cinemas are 1.85:1 and 2.39:1.
yes
In still camera photography, the most common aspect ratios are 4:3, 3:2,
4:3
In still camera photography, the most common aspect ratios are 4:3, 3:2,
yes
In still camera photography, the most common aspect ratios are 4:3, 3:2
3:2, 16:9, 5:3, 5:4, and 1:1

In still camera photography, the most common aspect ratios are 4:3, 3:2, and more recently being found in consumer cameras 16:9. Other aspect ratios, such as 5:3, 5:4, and 1:1 
describes the proportional relationship between its width and its height.
The aspect ratio of an image describes the proportional relationship between its width and its height.
two numbers separated by a colon
 It is commonly expressed as two numbers separated by a colon
no
 the width is divided into "x" units of equal length
the width
 the width is divided into "x" units
no
the height will be measured to be "y" units
the height
 the height will be measured to be "y" units. 
4:3 (1.3:1)
wo common videographic aspect ratios are 4:3 (1.3:1), the universal video format
no
Two common videographic aspect ratios are 4:3 (1.3:1), the universal video format of the 20th century
20th
Two common videographic aspect ratios are 4:3 (1.3:1), the universal video format of the 20th century
(1.7:1)
(1.7:1), universal for high-definition television and European digital television.
yes
Other aspect ratios, such as 5:3, 5:4, and 1:1 (square format), are used in photography as well, particularly in medium format and large format.
a colon
 It is commonly expressed as two numbers separated by a colon,