A covalent bond is a chemical bond involving the sharing of electron pairs between atoms. These electron pairs are typically held by both atoms in the bond, and the strength of the bond is determined by the number of electrons shared. Covalent bonds are the strongest type of chemical bond and are found in a wide variety of molecules, including water, carbon dioxide, and methane.

Some common examples of compounds that are made of covalent bonds include:

* Water (H2O): Water is a covalent compound made up of two hydrogen atoms and one oxygen atom. The oxygen atom shares two of its electrons with each of the hydrogen atoms, forming two covalent bonds.

* Carbon dioxide (CO2): Carbon dioxide is a covalent compound made up of one carbon atom and two oxygen atoms. The carbon atom shares two of its electrons with each of the oxygen atoms, forming two covalent bonds.

* Methane (CH4): Methane is a covalent compound made up of one carbon atom and four hydrogen atoms. The carbon atom shares four of its electrons with each of the hydrogen atoms, forming four covalent bonds.

Covalent bonds are also found in many other molecules, including organic molecules, inorganic molecules, and biological molecules.