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Of course there is nothing that can protect you from ALL bullets. Use your common sense Rosie. >:(
No. They are only capable of stopping pistol caliber bullets. Even some pistol rounds can penetrate a vest. Shotguns are also usually stopped by them. Most rifle rounds will tear through them. Unless you include body plate ceramic metal armor which is something else entirely and not really available to civilians.
There's no such thing as a "bullet proof" vest. That's advertising and Hollywood hype, not reality. Anyone that takes a bullet is going to be injured, anti-ballistic protection or not. The garment only serves as an attempt to minimize such damage.
There is a wide variety of anti-ballistic garments available these days though, including the traditional "vests" that offer protection to the torso. There's even anti-ballistic backpacks available for kids to carry their books to and from school. Aramid fiber (usually called by its DuPont-registered trademark name of Kevlar) is one of the more common choices for such garments. And there's a new "gel" in the works that will (apparently) absorb a fair bit of the hydrostatic shock as well as stopping, or slowing down the projectile.
None are 100% effective at stopping fired projectiles. They have the highest probability of effectiveness against lighter loads like small low and medium velocity rifle fire (ie. 22-caliber rimfire) and the more common pistol calibers (ie. 38 Special, 9-mm Parabellum). Their effectiveness drops to almost 0 when facing heavier caliber medium to high-velocity weapons, especially when they're firing projectiles designed to pierce armor (which will probably just punch a small hole through the victim and do little damage unless the projectile is "exploding" or passes through a major organ or blood vessel) . Adding such things as ceramic, plastic or metallic "trauma plates" can afford some additional protection to very critical areas such as over the heart (traditional vests have special pockets to accommodate these plates that can be purchased at the same place that sold you the vest, for another $100 to $400). But there's still the hydrostatic shock issue. The bullet stops but the shock wave of stopping that bullet has to go somewhere, usually into the body that the anti-ballistic material is to protect, often with devastating results. (No gaping wound but a LOT of tissue damage.)
And there's always the possibility that the garment itself will join the projectile in doing damage. I once read about the case of a deputy marshal (Federal, I believe) that was shot in the chest with a .45-70 Government rifle (a round developed in the middle of the last half of the 19 century). The projectile didn't penetrate the garment but did drag it along through the officer's body and out through his backbone.
