What Is 'url' When Specifying The Background-image?

Consider below code : . . . . . I'm not understanding what this url() does in above code means. I tried with

Solution 1:

URL is basically an address where to lock for the image. It can be a local path or some link to online storage.

URL stands for: Universal Resource Locator.

Solution 2:

URL is a CSS data type whose syntax (like rgb and rgba) require the value to go in parenthesis.

Solution 3:

The background-image property sets one or more background images for an element. you can use it under all HTML tag