It could be a belt, or a bearing, usually the Power Steering pump. Quickest way to tell if its a belt; spray the belts with "belt dressing". If its a power steering pump, it should get louder as you turn the wheel. Check the power steering fluid level.
you have a small cat stuck under your car
Assuming it is screeching in the area of the belt and pulleys, my problem was that the belt tensioner had seized and needed to be replaced. Noise problem was solved.
usually it is a loose belt
good chance the fan belt is slipping when driving may need tightning up this wouold cause a screeching noise.
You need to remove the serpentine belt, And then start engine and see if the noise goes away with the belt off. That will eliminate all the things that the belt runs. If your noise is still there with the belt off, then ask your question again saying that you have removed the belt and you have a high pitch screeching sound. Then wi'll see what we can do for you.
A slipping drive belt is one possibility.
most likely a loose or worn belt.
probably got a loose alternator belt..
Most commonly a loose belt or underinflated tire.
I think it is the time belt
you have a bad alternater or belt
Loose belt - will sound like a screeching noise.