Grinding - when the friction material on brake pads are heavily worn, this can result in a grinding noise as the brake pad has worn down to the metal caliper. This will likely damage the brake disc also.
Squeaking - there are many reasons why brakes squeal. It could suggest the brake caliper has stuck and the brakes pad remains partially applied to the disc but some pads have wear indicators that squeal when worn to let the driver know the brakes need changing. Either way, you should get this checked out.
Pulsating - If you feel a continuous pulsating from the brake pedal whenever you apply the brakes, this indicates the brake disc has become warped due to excessive heat. Pulsation occurs because the brake disc is distorted and no longer provides a perfectly flat surface when the brake pad makes contact. If this only occurs when you apply the brakes firmly, it could just be the ABS kicking in but you should have this checked out if you are concerned or it happens regularly.
Pulling - if your car pulls to the left or right when you apply the brakes this is usually indicative of a sticking hydraulic or mechanical component such as a seized caliper. An inspection can identify the precise reason for the vehicle pulling to one side.
Sponginess - the brake pedal feels spongy and the brakes seem unresponsive. This is a sign that air has entered the brakes lines and is preventing the brake fluid from flowing through this system effectively.
Soft Brake Pedal - if the brake pedal is limp and goes all the way to the floor, this indicates a serious braking system fault which you should have inspected immediately. A brake pedal that is soft and can be applied all the way to the floor usually means the brake fluid is ineffective and needs replacing but there can be several other potential reasons such as a master cylinder fault.
Dashboard Light - if a brake warning light appears on your instrument panel either continuously or when you apply the brakes it usually means the brake fluid level is critically low. This could also indicate a leak in the brake hoses.
High Handbrake - If the handbrake is pulling up higher than it normally does it may need adjusting. If the handbrake lever reaches the end of its travel it will fail the MOT.
Old Brake Fluid - If your brake fluid is over 2 years old it may lose its effectiveness. Brake fluid should be changed every to years.