Do shrapnel bullets exist?

Could you elaborate on the concept of shrapnel bullets? Are they a real type of ammunition or are they simply a product of fiction or misunderstanding? Are there any known instances where such bullets have been used in actual combat or conflict? Furthermore, what makes a bullet qualify as "shrapnel" and how does it differ from conventional bullets? Additionally, are there any safety concerns or regulations surrounding the use of shrapnel bullets, if they indeed exist?