There are several types of bonds, two of them are the covalent bond and the ionic bond.
Atoms possess a characteristic called electronegativity, electronegativity is the ability of an atom to attract electrons and varies depending on the atom.
When two atoms are forming a bond and have very different electronegativities, the bond will become ionic. An example is the salt sodium chloride, here chlorine is much more electronegative than sodium and therefore attracts more the electrons leaving sodium with a positive charge.
On the other hand, covalent bonds occur between atoms with similar electronegativities. Here the electrons are shared equally by both atoms and although there is a slight affinity for the more electronegative atom the difference is not strong enough to strip the electrons from one of the atoms. Examples of this are the carbon-hydrogen bonds in carbohydrates. Therefore, the answer is covalent bonds.