Is it really squealling, or chirping? Its possible that your brake pads are worn to the point where the wear indicator is sounding. You probably need new ones. If they are really squealling, you are probably scoring your disc rotor. Get it checked right away, you may be able to save some money, not just your or someone else's life.
This is probably due to worn brake rotors on the brakes, if there is no vibration when driving then this will be the cause.
If you are driving on wet roads there is no way to avoid those effects. Most brakes dry out very quickly when applied.
possibly a bad brake...you should get all brakes done
it could be that your brakes are dirty or that you need new pads
Glazed or loose fan belt?
Start with the most likely andeasiest to fix. Check your brake pads... There is a wear indicator on the inside pads (closest to engine) that will rub on the rotor and make a squealing noise to warn you that the pads are getting thin. When you apply the brakes the noise will go away a lot of the time. If the pads are new or not making the noise then I do not know what the problem may be.
you need to replace your belts. Take it to AutoZone to have them look at it
Probably a worn wheel bearing...have it looked at by a technician before it seizes.
Brakes
worn brakes could be the cause or check the A frame bushings
The brakes are the primary cause of stopping a car whilst driving.
Check for a vacuum leak around the throtle body and intake manifold.