Here's a breakdown:

* Covalent bonds occur when two or more atoms share electrons in their outermost shells (valence shells). This sharing allows the atoms to achieve a stable electron configuration, similar to that of noble gases.

* The shared electrons are attracted to the nuclei of both atoms, holding them together.

* Covalent bonds can be single, double, or triple, depending on the number of electron pairs being shared.

Here are some key features of covalent bonds:

* Strong bonds: Covalent bonds are generally stronger than other types of bonds, such as ionic bonds.

* Directional: Covalent bonds have a specific directionality, meaning that the shared electrons are located between the two nuclei. This gives molecules a specific shape.

* Non-polar and polar: Covalent bonds can be non-polar (equal sharing of electrons) or polar (unequal sharing of electrons).

Examples of molecules formed by covalent bonds:

* Water (H2O): Each hydrogen atom shares one electron with the oxygen atom, forming two single covalent bonds.

* Carbon dioxide (CO2): The carbon atom shares two electrons with each oxygen atom, forming two double covalent bonds.

* Methane (CH4): The carbon atom shares one electron with each of the four hydrogen atoms, forming four single covalent bonds.

Let me know if you'd like to learn more about specific types of covalent bonds or the properties of molecules formed by them.