Depends on caliber & velocity of the bullet.
Answer is Kevlar.
Kevlar fabric
Bullet proof Vests
Kevlar
The best-known bullet-proof material is probably Kevlar.
Bullet-proof vests are made of Kevlar as are motorcycle re-enforcement pads. Kevlar is extremely strong weave of synthetic fibre which has the added feature of being flexible.
Kevlar is a very dense polyamide. It has a high tensile strength, making it useful in several ways, such as bullet-proof vests.
It is used as a bullet-proof material and also, surprisingly, canoes.
It's a special kind of polymer, related to nylon, woven in certain patterns that enhance its ability to absorb and redirect the energy from a bullet. Note, that Kevlar (and all related materials) aren't really bullet "proof", rather they are bullet "resistant". They resist the passage of a bullet - for certain size and speed bullets, this resistance is enough to prevent it passing through the material, but for others, the bullet still retains enough energy to penetrate the material. Thus, all bullet resistant materials and designs are rated according to the type of bullet they are able to stop.
Kevlar is used to stop some bullets. Normally it will stop pistol rounds but other rounds , especially an anti tank round.
I don't understand what your asking but, kevlar body armor is an example of a layered fiber that catches the bullet while dissapating its energy, if that's what your asking.