Final answer:
The 'vh' unit is the fluid measurement type that returns a percentage of the viewport height, where '50vh' would be half of the screen's height.
Step-by-step explanation:
The fluid measurement type that returns a percentage of the viewport height is vh. The vh unit stands for viewport height and it's a relative unit that allows designers and developers to size an element to be a specific percentage of the viewport height, regardless of the actual size of the device's screen. For example, if you set an element's height to 50vh, it will take up 50% of the viewport height.