Why is the use of specifying width and height in svg attribute?

Answer 1

Suppose you have a code like this
<svg>width=100 height=90(this is an example not a real code)
If create a circle with radius 200,the circle will be split to half but
If a rect and the width is greater than 100 the rect will also be split
I hope you understand this example

Answer 2

Oh great. So it specifically create an space for the graphical objects.