No, not all compounds are made by sharing electrons. While sharing electrons (covalent bonding) is a very common way for atoms to form compounds, there's another important way: ionic bonding.

Ionic bonding occurs when one atom completely transfers an electron to another atom. This creates ions:

* Cations: Positively charged ions formed when an atom loses an electron.

* Anions: Negatively charged ions formed when an atom gains an electron.

The opposite charges of the ions then attract each other, forming a compound.

Here's an example:

* Sodium (Na) has one electron in its outer shell and readily loses it to become a positively charged sodium ion (Na+).

* Chlorine (Cl) has seven electrons in its outer shell and readily gains one electron to become a negatively charged chloride ion (Cl-).

The attraction between the Na+ and Cl- ions forms the compound sodium chloride (NaCl), or table salt.

In summary:

* Covalent bonding: Sharing electrons between atoms.

* Ionic bonding: Transferring electrons between atoms.

So, while covalent bonding is common, not all compounds are formed by sharing electrons. Ionic bonding plays a crucial role in the formation of many important compounds.