My brakes are making a squeaking and grinding noise when braking. Why?

It's a 2001 Ford Focus

Tire for new brakes

Probably because they need maintenance… Pads replaced, rotors, the works

Brakes are made with a little steel post in the pad that gets exposed as the pad wears. This is a feature to let you know when they are low because you hear it. That metal post is rubbing against the rotor, making a sound, telling you that you need new pads. Usually you still have some life left, but I wouldn't wait very long because at some point they could fail.

It's time to replace them

Probably because the pads are worn out and you've damaged the rotors.

Time for your mechanic to have a look. The pads are definitely worn, perhaps the rotors are also scored.

Probably are running out of brake pad and the caliper is now hitting the rotor.

Time to get a new car.

You see a mechanic to find out what is wrong.

Most likely the brake pads/shoes friction material is completely worn down to nothing.