background-attachment property, you can specify whether or not a background image should remain at one position on the web page or whether it should move up and down as the user scrolls through a web page.
background-attachment property can take one of two values:
scroll - this value allows the image to move up and down as a user scrolls on the web page (this is the default value).
fixed - this value pins the image's position on the page.
background: url("#") no-repeat right center;
In the example above, the background image will remained fixed as a user scrolls through the web page.