What is a chemical bond formed by the transfer of electrons?
Bonds are of three types:
1) Ionic bond- some chemical species donate electrons and some accept electrons. The charged species are held together by electrostatic force of attraction.
2)Covalent bond- Some electrons from each atom are shared by all the atoms such that those electrons complete the octet of each contributing atom.
3)Metallic bond- It is seen in metals where the outermost electrons of all the atoms are free to move through out the bulk of the material.
Hence the answer is ionic bond.