What is vh and vw

Question

I've seen develpers using vh and vw to adjust height and width of Font and other element but I don't know what are these.
So Please explain this

Answer 1

These are viewport units, i.e. viewport height (vh) and viewport width (vw). It specifies the height and width of an element relative to the viewport (browser). The difference between these units and % is that the former is relative to the viewport and the latter is relative to the parent height/width.