While it goes without saying that the brake system on any vehicle has an incredibly important job, I wanted to pull the wheel here just to show you the very basics of a brake system.
This is the caliper. It holds the pads, both front and rear together, so that they can squeeze this rotor which is the spinning part of the wheel. Just like on a bicycle these pads, through the caliper, squeeze the spinning rotor and ultimately stop your vehicle.
This rotor is showing some wear, and will need to be replaced the next time we replace the pads. Grooves or cuts in the rotor's surface, front or back, are a sure sign of needing new rotors.
Many of today's vehicles use ABS, or Anti Lock Braking Systems. Note the wiring to the ABS speed sensor and be sure there's a good connection and no obstructions on the wire.
Finally, check your brake fluid level. Brake fluid can be found under the hood, in the master cylinder reservoir, similar to this one, and is always located on the driver's side of the vehicle. Ours needs to be topped off.
Be sure you always use new brake fluid that meets the requirements noted in your owner's manual.